Add support for XEP-0350: Data Forms Geolocation Element

Fixes SMACK-871.

.travis.yml

@@ -1,7 +1,7 @@
 language: android
 android:
   components:
-    - android-16
+    - android-19
 jdk:
   - oraclejdk8
   - openjdk8
@@ -11,7 +11,7 @@ cache:
   - $HOME/.m2
 
 before_install:
-  - export GRADLE_VERSION=5.1.1
+  - export GRADLE_VERSION=5.2.1
   - wget https://services.gradle.org/distributions/gradle-${GRADLE_VERSION}-all.zip
   - unzip -q gradle-${GRADLE_VERSION}-all.zip
   - export PATH="$(pwd)/gradle-${GRADLE_VERSION}/bin:$PATH"

build.gradle

@@ -14,8 +14,8 @@ buildscript {
 }
 
 plugins {
-    id 'ru.vyarus.animalsniffer' version '1.4.6'
-	id 'net.ltgt.errorprone' version '0.6'
+    id 'ru.vyarus.animalsniffer' version '1.5.0'
+	id 'net.ltgt.errorprone' version '0.8'
 }
 
 apply plugin: 'org.kordamp.gradle.markdown'
@@ -24,6 +24,7 @@ apply from: 'version.gradle'
 
 allprojects {
 	apply plugin: 'java'
+	apply plugin: 'java-library'
 	apply plugin: 'eclipse'
 	apply plugin: 'idea'
 	apply plugin: 'jacoco'
@@ -80,6 +81,8 @@ allprojects {
 			':smack-omemo',
 			':smack-omemo-signal',
 			':smack-openpgp',
+			':smack-xmlparser',
+			':smack-xmlparser-xpp3',
 		].collect{ project(it) }
 		androidBootClasspathProjects = [
 			':smack-android',
@@ -97,13 +100,37 @@ allprojects {
 			':smack-omemo-signal',
 			':smack-omemo-signal-integration-test',
 		].collect{ project(it) }
+		// When this list is empty, then move the according javadoc
+		// tool Werror option into the global configure section.
+		nonStrictJavadocProjects = [
+			':smack-bosh',
+			':smack-core',
+			':smack-experimental',
+			':smack-extensions',
+			':smack-im',
+			':smack-integration-test',
+			':smack-jingle-old',
+			':smack-legacy',
+			':smack-omemo',
+			':smack-tcp',
+		].collect{ project(it) }
 		// Lazily evaluate the Android bootClasspath and offline
 		// Javadoc using a closure, so that targets which do not
 		// require it are still able to succeed without an Android
 		// SDK.
 		androidBootClasspath = { getAndroidRuntimeJar() }
 		androidJavadocOffline = { getAndroidJavadocOffline() }
-		junitVersion = '5.2.0'
+		junit4Projects = [
+			':smack-core',
+			':smack-extensions',
+			':smack-im',
+			':smack-integration-test',
+			':smack-omemo',
+			':smack-omemo-signal',
+			':smack-openpgp',
+		].collect { project(it) }
+		junitVersion = '5.4.2'
+		powerMockVersion = '2.0.2'
 	}
 	group = 'org.igniterealtime.smack'
 	sourceCompatibility = JavaVersion.VERSION_1_8
@@ -114,6 +141,10 @@ allprojects {
 	}
 
 	test {
+		useJUnitPlatform()
+
+		maxParallelForks = Runtime.runtime.availableProcessors().intdiv(2) ?: 1
+
 		// Enable full stacktraces of failed tests. Especially handy
 		// for environments like Travis.
 		testLogging {
@@ -170,21 +201,25 @@ allprojects {
 			'-Xlint:-options',
 			'-Werror',
 		]
-		options.errorprone.errorproneArgs = [
-			// Disable errorprone checks
-			'-Xep:TypeParameterUnusedInFormals:OFF',
-			// Disable errorpone StringSplitter check, as it
-			// recommends using Splitter from Guava, which we don't
-			// have (nor want to use in Smack).
-			'-Xep:StringSplitter:OFF',
-			'-Xep:JdkObsolete:OFF',
-			// Disabled because sinttest re-uses BeforeClass from junit.
-			// TODO: change sinttest so that it has it's own
-			// BeforeClass and re-enable this check.
-			'-Xep:JUnit4ClassAnnotationNonStatic:OFF',
-			// Disabled but should be re-enabled at some point
-			//'-Xep:InconsistentCapitalization:OFF',
-		]
+		options.errorprone {
+			error("UnusedVariable", "UnusedMethod")
+			errorproneArgs = [
+				// Disable errorprone checks
+				'-Xep:TypeParameterUnusedInFormals:OFF',
+				// Disable errorpone StringSplitter check, as it
+				// recommends using Splitter from Guava, which we don't
+				// have (nor want to use in Smack).
+				'-Xep:StringSplitter:OFF',
+				'-Xep:JdkObsolete:OFF',
+				// Disabled because sinttest re-uses BeforeClass from junit.
+				// TODO: change sinttest so that it has it's own
+				// BeforeClass and re-enable this check.
+				'-Xep:JUnit4ClassAnnotationNonStatic:OFF',
+				// Disabled but should be re-enabled at some point
+				//'-Xep:InconsistentCapitalization:OFF',
+				'-Xep:MixedMutabilityReturnType:OFF',
+			]
+		}
 	}
 
 	tasks.withType(ScalaCompile) {
@@ -232,7 +267,11 @@ allprojects {
 	}
 
 	dependencies {
-		errorprone 'com.google.errorprone:error_prone_core:2.3.2'
+		testImplementation "org.junit.jupiter:junit-jupiter-api:$junitVersion"
+		testImplementation "org.junit.jupiter:junit-jupiter-params:$junitVersion"
+		testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
+
+		errorprone 'com.google.errorprone:error_prone_core:2.3.3'
 		errorproneJavac('com.google.errorprone:javac:9+181-r4173-1')
 	}
 
@@ -241,6 +280,15 @@ allprojects {
 	test { dependsOn javadoc }
 }
 
+configure (junit4Projects) {
+	dependencies {
+		testImplementation "org.junit.vintage:junit-vintage-engine:$junitVersion"
+		testImplementation "org.powermock:powermock-module-junit4:$powerMockVersion"
+		testImplementation "org.powermock:powermock-module-junit4-rule:$powerMockVersion"
+		testImplementation "org.powermock:powermock-api-mockito2:$powerMockVersion"
+	}
+}
+
 gradle.taskGraph.whenReady { taskGraph ->
 	if (signingRequired
 		&& taskGraph.allTasks.any { it instanceof Sign }) {
@@ -519,19 +567,21 @@ configure(integrationTestProjects + project(':smack-repl')) {
 project(':smack-omemo').clirr.enabled = false
 project(':smack-omemo-signal').clirr.enabled = false
 
-configure(
-	[ ':smack-omemo',
-	  ':smack-omemo-signal',
-	  ':smack-omemo-signal-integration-test',
-	].collect{ project(it) }) {
-}
-
 subprojects*.jar {
    manifest {
        from sharedManifest
    }
 }
 
+configure(subprojects - nonStrictJavadocProjects) {
+	tasks.withType(Javadoc) {
+		// Abort on javadoc warnings.
+		// See JDK-8200363 (https://bugs.openjdk.java.net/browse/JDK-8200363)
+		// for information about the -Xwerror option.
+		options.addStringOption('Xwerror', '-quiet')
+	}
+}
+
 configure(subprojects - gplLicensedProjects) {
 	checkstyle {
 		configProperties.checkstyleLicenseHeader = "header"
@@ -646,15 +696,7 @@ def getGitCommit() {
 }
 
 def getAndroidRuntimeJar() {
-	// We set a different Android API level compared to
-	// smackMinAndroidSdk here. The runtime jar retrieved via this
-	// method is, compared to earlier Smack versions, not used to
-	// check for Android API compatibility. Instead it is used to for
-	// the eclipse classpath, for javadoc and when compiling the pure
-	// Android subprojects of Smack. Currently we require level 16
-	// here, because of the @TargetApi annotation found in
-	// AndroidUsingLinkProperties of minidns-android21.
-	def androidApiLevel = 16
+	def androidApiLevel = ext.smackMinAndroidSdk
 	def androidHome = getAndroidHome()
 	def androidJar = new File("$androidHome/platforms/android-${androidApiLevel}/android.jar")
 	if (androidJar.isFile()) {

config/checkstyle.xml

@@ -39,12 +39,7 @@
 		<property name="format" value="^\s+$"/>
 		<property name="message" value="Line containing only whitespace character(s)"/>
 	</module>
-	<module name="RegexpSingleline">
-		<!-- We use {2,} instead of + here to address the typical case where a file was written
-		   with tabs but javadoc is causing '\t *' -->
-		<property name="format" value="^\t+ {2,}"/>
-		<property name="message" value="Line containing space(s) after tab(s)"/>
-	</module>
+	<module name="FileTabCharacter"/>
 	<module name="RegexpSingleline">
 		<!--
 			Explaining the following Regex
@@ -147,6 +142,7 @@
 										 , LITERAL_DO
 										 , LITERAL_FOR
 										 , DO_WHILE
+										 , COMMA
 										 "/>
 		</module>
 		<module name="WhitespaceAround">

documentation/developer/provider.md

@@ -27,11 +27,11 @@ public MyExtension parse(XmlPullParser parser, int initialDepth) {
   outerloop: while(true) {
     // Make sure to have already parse all attributes of the outermost element,
     // i.e. 'attrFoo' of 'myExtension' in this example. Then advance the parser
-    int event = parser.next();
+    XmlPullParser.Event event = parser.next();
 
     // Use switch/case of int instead of a if/else-if cascade
     switch (event) {
-    case XmlPullParser.START_TAG:
+    case START_ELEMENT:
       // Determine the name of the element which start tag we are seeing
       String name = parser.getName();
       // We can use switch/case of Strings since Java7, make use of its advantages
@@ -52,12 +52,15 @@ public MyExtension parse(XmlPullParser parser, int initialDepth) {
         break;
       }
       break;
-    case XmlPullParser.END_TAG:
+    case END_ELEMENT:
       // The abort condition with the break labeled loop statement
       if (parser.getDepth() == initialDepth) {
         break outerloop;
       }
       break;
+    default:
+      // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+      break;
     }
   }
 

documentation/extensions/index.md

@@ -56,23 +56,25 @@ Smack Extensions and currently supported XEPs of smack-extensions
 | [SI File Transfer](filetransfer.md)         | [XEP-0096](https://xmpp.org/extensions/xep-0096.html)  | n/a       | Transfer files between two users over XMPP. |
 | User Mood                                   | [XEP-0107](https://xmpp.org/extensions/xep-0107.html)  | 1.2.1     | Communicate the users current mood. |
 | [Entity Capabilities](caps.md)              | [XEP-0115](https://xmpp.org/extensions/xep-0115.html)  | n/a       | Broadcasting and dynamic discovery of entity capabilities. |
-| [Jingle](jingle.html)                       | [XEP-0116](https://xmpp.org/extensions/xep-0166.html)  | n/a       | Initiate and manage sessions between two XMPP entities. |
 | Data Forms Validation                       | [XEP-0122](https://xmpp.org/extensions/xep-0122.html)  | n/a       | Enables an application to specify additional validation guidelines . |
 | Service Administration                      | [XEP-0133](https://xmpp.org/extensions/xep-0133.html)  | n/a       | Recommended best practices for service-level administration of servers and components using Ad-Hoc Commands. |
 | Stream Compression                          | [XEP-0138](https://xmpp.org/extensions/xep-0138.html)  | n/a       | Support for optional compression of the XMPP stream.
 | Data Forms Layout                           | [XEP-0141](https://xmpp.org/extensions/xep-0141.html)  | n/a       | Enables an application to specify form layouts. |
 | Personal Eventing Protocol                  | [XEP-0163](https://xmpp.org/extensions/xep-0163.html)  | n/a       | Using the XMPP publish-subscribe protocol to broadcast state change events associated with an XMPP account. |
+| [Jingle](jingle.html)                       | [XEP-0166](https://xmpp.org/extensions/xep-0166.html)  | n/a       | Initiate and manage sessions between two XMPP entities. |
 | Message Delivery Receipts                   | [XEP-0184](https://xmpp.org/extensions/xep-0184.html)  | n/a       | Extension for message delivery receipts. The sender can request notification that the message has been delivered. |
 | [Blocking Command](blockingcommand.md)      | [XEP-0191](https://xmpp.org/extensions/xep-0191.html)  | n/a       | Communications blocking that is intended to be simpler than privacy lists (XEP-0016). |
 | XMPP Ping                                   | [XEP-0199](https://xmpp.org/extensions/xep-0199.html)  | n/a       | Sending application-level pings over XML streams.
 | Entity Time                                 | [XEP-0202](https://xmpp.org/extensions/xep-0202.html)  | n/a       | Allows entities to communicate their local time |
 | Delayed Delivery                            | [XEP-0203](https://xmpp.org/extensions/xep-0203.html)  | n/a       | Extension for communicating the fact that an XML stanza has been delivered with a delay. |
 | XMPP Over BOSH                              | [XEP-0206](https://xmpp.org/extensions/xep-0206.html)  | n/a       | Use Bidirectional-streams Over Synchronous HTTP (BOSH) to transport XMPP stanzas. |
+| Data Forms Media Element                    | [XEP-0221](https://xmpp.org/extensions/xep-0221.html)  | n/a       | Allows to include media data in XEP-0004 data forms. |
 | Attention                                   | [XEP-0224](https://xmpp.org/extensions/xep-0224.html)  | n/a       | Getting attention of another user. |
 | Bits of Binary                              | [XEP-0231](https://xmpp.org/extensions/xep-0231.html)  | n/a       | Including or referring to small bits of binary data in an XML stanza. |
 | Best Practices for Resource Locking         | [XEP-0296](https://xmpp.org/extensions/xep-0296.html)  | n/a       | Specifies best practices to be followed by Jabber/XMPP clients about when to lock into, and unlock away from, resources. |
 | Last Message Correction                     | [XEP-0308](https://xmpp.org/extensions/xep-0308.html)  | n/a       | Provides a method for indicating that a message is a correction of the last sent message. |
 | Last User Interaction in Presence           | [XEP-0319](https://xmpp.org/extensions/xep-0319.html)  | n/a       | Communicate time of last user interaction via XMPP presence notifications. |
+| Data Forms Geolocation Element              | [XEP-0350](https://xmpp.org/extensions/xep-0350.html)  | n/a       | Allows to include XEP-0080 gelocation data in XEP-0004 data forms.  |
 | [Group Chat Invitations](invitation.md)     | n/a                                                    | n/a       | Send invitations to other users to join a group chat room. |
 | [Jive Properties](properties.md)            | n/a                                                    | n/a       | TODO |
 

documentation/providers.md

@@ -23,7 +23,7 @@ Whenever a packet extension is found in a packet, parsing will be
 passed to the correct provider. Each provider must extend the
 ExtensionElementProvider abstract class. Each extension provider is
 responsible for parsing the raw XML stream, via the
-[XML Pull Parser](http://www.xmlpull.org/), to contruct an object.
+Smack's `XmlPullParser` interface, to construct an object.
 
 You can also create an introspection provider
 (`provider.IntrospectionProvider.PacketExtensionIntrospectionProvider`). Here,
@@ -161,9 +161,9 @@ public class MyIQProvider extends IQProvider<MyIQ> {
 
     // Start parsing loop
     outerloop: while(true) {
-      int eventType = parser.next();
+      XmlPullParser.Event eventType = parser.next();
       switch(eventType) {
-      case XmlPullParser.START_TAG:
+      case START_ELEMENT:
         String elementName = parser.getName();
         switch (elementName) {
         case "user":
@@ -175,12 +175,15 @@ public class MyIQProvider extends IQProvider<MyIQ> {
           break;
         }
         break;
-      case XmlPullParser.END_TAG:
+      case END_ELEMENT:
         // Abort condition: if the are on a end tag (closing element) of the same depth
         if (parser.getDepth() == initialDepth) {
           break outerloop;
         }
         break;
+      default:
+        // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+        break;
       }
     }
 
@@ -225,9 +228,9 @@ _Disco Items IQProvider_
 			String node = "";
 			discoverItems.setNode(parser.getAttributeValue("", "node"));
 			outerloop: while (true) {
-				int eventType = parser.next();
+				XmlPullParser.Event eventType = parser.next();
 				switch (eventType) {
-				case XmlPullParser.START_TAG:
+				case START_ELEMENT:
 					String elementName = parser.getName();
 					switch (elementName) {
 					case "item":
@@ -239,7 +242,7 @@ _Disco Items IQProvider_
 						break;
 					}
 					break;
-				case XmlPullParser.END_TAG:
+				case END_ELEMENT:
 					String elementName = parser.getName();
 					switch (elementName) {
 					case "item":
@@ -295,17 +298,17 @@ _Subscription PacketExtensionProvider Implementation_
 			String state = parser.getAttributeValue(null, "subscription");
 			boolean isRequired = false;
 
-			int tag = parser.next();
+			XmlPullParser.Event tag = parser.next();
 
-			if ((tag == XmlPullParser.START_TAG) && parser.getName().equals("subscribe-options")) {
+			if ((tag == XmlPullParser.START_ELEMENT) && parser.getName().equals("subscribe-options")) {
 				tag = parser.next();
 
-				if ((tag == XmlPullParser.START_TAG) && parser.getName().equals("required"))
+				if ((tag == XmlPullParser.START_ELEMENT) && parser.getName().equals("required"))
 					isRequired = true;
 
-				while (parser.next() != XmlPullParser.END_TAG && parser.getName() != "subscribe-options");
+				while (parser.next() != XmlPullParser.END_ELEMENT && parser.getName() != "subscribe-options");
 			}
-			while (parser.getEventType() != XmlPullParser.END_TAG) parser.next();
+			while (parser.getEventType() != XmlPullParser.END_ELEMENT) parser.next();
 			return new Subscription(jid, nodeId, subId, state == null ? null : Subscription.State.valueOf(state), isRequired);
 		}
 	}

resources/releasedocs/README.html

@@ -169,14 +169,10 @@ recommended when using Smack.
 </p>
 
 <p>
-If you dont' use a
-dependency resolution system, like gradle or maven, then you will need
-to download at least
-the <a href="http://www.extreme.indiana.edu/xgws/xsoap/xpp/mxp1/">Xml
-Pull Parser 3rd Edition (XPP3) library</a> or any other library that
-implements the XmlPullParser interface
-(like <a href="http://kxml.org/">kXML</a>) and the set of
-<a href="http://jxmpp.org">jXMPP libraries</a>.
+  Smack tries to depend on as few as possible libraries. The only
+  requirement is <a href="http://jxmpp.org">jXMPP</a>. For DNS
+  resolution we recommend to
+  use <a href="http://minidns.org">MiniDNS</a>.
 </p>
 
 <p>

settings.gradle

@@ -28,4 +28,7 @@ include 'smack-core',
 		'smack-omemo-signal',
 		'smack-omemo-signal-integration-test',
 		'smack-repl',
-		'smack-openpgp'
+		'smack-openpgp',
+		'smack-xmlparser',
+		'smack-xmlparser-stax',
+		'smack-xmlparser-xpp3'

smack-android/build.gradle

@@ -7,6 +7,7 @@ smack-extensions and smack-experimental."""
 // Note that the test dependencies (junit, …) are inferred from the
 // sourceSet.test of the core subproject
 dependencies {
+	api project(':smack-xmlparser-xpp3')
 	// Depend on minidns-android21 as optional dependency, even if may
 	// not need it. Can't hurt to have it in the programm path with
 	// the correct MiniDNS version as it won't hurt even if the

smack-android/src/main/java/org/jivesoftware/smack/util/stringencoder/android/AndroidBase64UrlSafeEncoder.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014-2018 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,9 +16,8 @@
  */
 package org.jivesoftware.smack.util.stringencoder.android;
 
-import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 
-import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.stringencoder.StringEncoder;
 
 import android.util.Base64;
@@ -39,21 +38,13 @@ public final class AndroidBase64UrlSafeEncoder implements StringEncoder<String>
 
     @Override
     public String encode(String string) {
-        try {
-            return Base64.encodeToString(string.getBytes(StringUtils.UTF8), BASE64_ENCODER_FLAGS);
-        } catch (UnsupportedEncodingException e) {
-            throw new IllegalStateException("UTF-8 not supported", e);
-        }
+        return Base64.encodeToString(string.getBytes(StandardCharsets.UTF_8), BASE64_ENCODER_FLAGS);
     }
 
     @Override
     public String decode(String string) {
         byte[] bytes = Base64.decode(string, BASE64_ENCODER_FLAGS);
-        try {
-            return new String(bytes, StringUtils.UTF8);
-        } catch (UnsupportedEncodingException e) {
-            throw new IllegalStateException("UTF-8 not supported", e);
-        }
+        return new String(bytes, StandardCharsets.UTF_8);
     }
 
 }

smack-bosh/src/main/java/org/jivesoftware/smack/bosh/XMPPBOSHConnection.java

@@ -20,7 +20,6 @@ package org.jivesoftware.smack.bosh;
 import java.io.IOException;
 import java.io.PipedReader;
 import java.io.PipedWriter;
-import java.io.StringReader;
 import java.io.Writer;
 import java.util.Map;
 import java.util.logging.Level;
@@ -44,6 +43,7 @@ import org.jivesoftware.smack.sasl.packet.SaslStreamElements.SASLFailure;
 import org.jivesoftware.smack.sasl.packet.SaslStreamElements.Success;
 import org.jivesoftware.smack.util.CloseableUtil;
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 import org.igniterealtime.jbosh.AbstractBody;
 import org.igniterealtime.jbosh.BOSHClient;
@@ -56,11 +56,8 @@ import org.igniterealtime.jbosh.BOSHException;
 import org.igniterealtime.jbosh.BOSHMessageEvent;
 import org.igniterealtime.jbosh.BodyQName;
 import org.igniterealtime.jbosh.ComposableBody;
-
 import org.jxmpp.jid.DomainBareJid;
 import org.jxmpp.jid.parts.Resourcepart;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserFactory;
 
 /**
  * Creates a connection to an XMPP server via HTTP binding.
@@ -479,14 +476,13 @@ public class XMPPBOSHConnection extends AbstractXMPPConnection {
                     if (streamId == null) {
                         streamId = body.getAttribute(BodyQName.create(XMPPBOSHConnection.BOSH_URI, "authid"));
                     }
-                    final XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
-                    parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
-                    parser.setInput(new StringReader(body.toXML()));
-                    int eventType = parser.getEventType();
+                    final XmlPullParser parser = PacketParserUtils.getParserFor(body.toXML());
+
+                    XmlPullParser.Event eventType = parser.getEventType();
                     do {
                         eventType = parser.next();
                         switch (eventType) {
-                        case XmlPullParser.START_TAG:
+                        case START_ELEMENT:
                             String name = parser.getName();
                             switch (name) {
                             case Message.ELEMENT:
@@ -528,9 +524,12 @@ public class XMPPBOSHConnection extends AbstractXMPPConnection {
                                 }
                             }
                             break;
+                        default:
+                            // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                            break;
                         }
                     }
-                    while (eventType != XmlPullParser.END_DOCUMENT);
+                    while (eventType != XmlPullParser.Event.END_DOCUMENT);
                 }
                 catch (Exception e) {
                     if (isConnected()) {

smack-core/build.gradle

@@ -2,23 +2,27 @@ description = """\
 Smack core components."""
 
 ext {
-	xmlUnitVersion = "2.6.0"
-	powerMockVersion = "1.7.3"
+	xmlUnitVersion = '2.6.2'
 }
 
 dependencies {
-	compile 'xpp3:xpp3:1.1.4c'
+	compile project(':smack-xmlparser')
 	compile "org.jxmpp:jxmpp-core:$jxmppVersion"
 	compile "org.jxmpp:jxmpp-jid:$jxmppVersion"
 	compile "org.minidns:minidns-core:$miniDnsVersion"
+	testCompile project(':smack-xmlparser-stax')
+	testCompile project(':smack-xmlparser-xpp3')
 	testCompile "org.jxmpp:jxmpp-jid:$jxmppVersion:tests"
-	testCompile "org.junit.jupiter:junit-jupiter-api:$junitVersion"
-	testCompile "org.junit.vintage:junit-vintage-engine:$junitVersion"
 	testCompile "org.xmlunit:xmlunit-core:$xmlUnitVersion"
-	testCompile "org.xmlunit:xmlunit-legacy:$xmlUnitVersion"
-	testCompile "org.powermock:powermock-module-junit4:$powerMockVersion"
-	testCompile "org.powermock:powermock-module-junit4-rule:$powerMockVersion"
-	testCompile "org.powermock:powermock-api-mockito2:$powerMockVersion"
+	// Explictily add assertj-core which is a dependency of
+	// xmlunit-assertj, but gradle fails to resolves it with:
+	// Execution failed for task ':smack-core:compileTestJava'.
+	// > Could not resolve all files for configuration ':smack-core:testCompileClasspath'.
+	//    > Could not find org.assertj:assertj-core:.
+	//		 Required by:
+	//			 project :smack-core > org.xmlunit:xmlunit-assertj:2.6.2
+	testCompile "org.assertj:assertj-core:3.11.1"
+	testCompile "org.xmlunit:xmlunit-assertj:$xmlUnitVersion"
 	testCompile 'com.jamesmurty.utils:java-xmlbuilder:1.2'
 }
 

smack-core/src/integration-test/java/org/jivesoftware/smack/packet/PrivacyProviderTest.java

@@ -16,9 +16,9 @@ package org.jivesoftware.smack.packet;
 
 import org.jivesoftware.smack.provider.PrivacyProvider;
 import org.jivesoftware.smack.test.SmackTestCase;
-import org.xmlpull.v1.XmlPullParserFactory;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParserFactory;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import java.io.StringReader;
 

smack-core/src/integration-test/java/org/jivesoftware/smack/test/SmackTestCase.java

@@ -32,8 +32,8 @@ import org.jivesoftware.smack.ConnectionConfiguration;
 import org.jivesoftware.smack.TCPConnection;
 import org.jivesoftware.smack.XMPPException;
 import org.jivesoftware.smack.util.ConnectionUtils;
-import org.xmlpull.v1.XmlPullParserFactory;
-import org.xmlpull.v1.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserFactory;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 /**
  * Base class for all the test cases which provides a pre-configured execution context. This
@@ -414,9 +414,9 @@ public abstract class SmackTestCase extends TestCase {
             XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
             parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
             parser.setInput(systemStream, "UTF-8");
-            int eventType = parser.getEventType();
+            XmlPullParser.Event eventType = parser.getEventType();
             do {
-                if (eventType == XmlPullParser.START_TAG) {
+                if (eventType == START_ELEMENT) {
                     if (parser.getName().equals("host")) {
                         host = parser.nextText();
                     }
@@ -459,7 +459,7 @@ public abstract class SmackTestCase extends TestCase {
                 }
                 eventType = parser.next();
             }
-            while (eventType != XmlPullParser.END_DOCUMENT);
+            while (eventType != END_DOCUMENT);
             parsedOK = true;
         }
         catch (Exception e) {

smack-core/src/integration-test/java/org/jivesoftware/smack/util/XMPPErrorTest.java

@@ -20,9 +20,9 @@ import java.io.StringReader;
 
 import org.jivesoftware.smack.packet.XMPPError;
 import org.jivesoftware.smack.test.SmackTestCase;
-import org.xmlpull.v1.XmlPullParserFactory;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParserFactory;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 public class XMPPErrorTest extends SmackTestCase {
 

smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java

@@ -23,6 +23,7 @@ import java.io.InputStream;
 import java.io.Reader;
 import java.io.Writer;
 import java.lang.reflect.Constructor;
+import java.nio.charset.StandardCharsets;
 import java.security.KeyManagementException;
 import java.security.KeyStore;
 import java.security.KeyStoreException;
@@ -64,6 +65,7 @@ import javax.net.ssl.X509TrustManager;
 import javax.security.auth.callback.Callback;
 import javax.security.auth.callback.CallbackHandler;
 import javax.security.auth.callback.PasswordCallback;
+import javax.xml.namespace.QName;
 
 import org.jivesoftware.smack.ConnectionConfiguration.DnssecMode;
 import org.jivesoftware.smack.ConnectionConfiguration.SecurityMode;
@@ -121,6 +123,8 @@ import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.dns.HostAddress;
 import org.jivesoftware.smack.util.dns.SmackDaneProvider;
 import org.jivesoftware.smack.util.dns.SmackDaneVerifier;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jxmpp.jid.DomainBareJid;
 import org.jxmpp.jid.EntityFullJid;
@@ -130,8 +134,6 @@ import org.jxmpp.jid.parts.Resourcepart;
 import org.jxmpp.stringprep.XmppStringprepException;
 import org.jxmpp.util.XmppStringUtils;
 import org.minidns.dnsname.DnsName;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
 
 
 /**
@@ -233,11 +235,11 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
 
     private XmlEnvironment incomingStreamXmlEnvironment;
 
-    final Map<String, NonzaCallback> nonzaCallbacks = new HashMap<>();
+    final Map<QName, NonzaCallback> nonzaCallbacks = new HashMap<>();
 
     protected final Lock connectionLock = new ReentrantLock();
 
-    protected final Map<String, FullyQualifiedElement> streamFeatures = new HashMap<>();
+    protected final Map<QName, FullyQualifiedElement> streamFeatures = new HashMap<>();
 
     /**
      * The full JID of the authenticated user, as returned by the resource binding response of the server.
@@ -336,6 +338,12 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
             Thread thread = new Thread(runnable);
             thread.setName("Smack Cached Executor");
             thread.setDaemon(true);
+            thread.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
+                @Override
+                public void uncaughtException(Thread t, Throwable e) {
+                    LOGGER.log(Level.WARNING, t + " encountered uncaught exception", e);
+                }
+            });
             return thread;
         }
     });
@@ -381,8 +389,8 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
 
     protected Exception currentConnectionException;
 
-    private final Map<String, IQRequestHandler> setIqRequestHandler = new HashMap<>();
-    private final Map<String, IQRequestHandler> getIqRequestHandler = new HashMap<>();
+    private final Map<QName, IQRequestHandler> setIqRequestHandler = new HashMap<>();
+    private final Map<QName, IQRequestHandler> getIqRequestHandler = new HashMap<>();
 
     /**
      * Create a new XMPPConnection to an XMPP server.
@@ -1213,7 +1221,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
     protected final void parseAndProcessNonza(XmlPullParser parser) throws IOException, XmlPullParserException, SmackParsingException {
         final String element = parser.getName();
         final String namespace = parser.getNamespace();
-        final String key = XmppStringUtils.generateKey(element, namespace);
+        final QName key = new QName(namespace, element);
 
         NonzaProvider<? extends Nonza> nonzaProvider = ProviderManager.getNonzaProvider(key);
         if (nonzaProvider == null) {
@@ -1243,7 +1251,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         try {
             stanza = PacketParserUtils.parseStanza(parser, incomingStreamXmlEnvironment);
         }
-        catch (Exception e) {
+        catch (XmlPullParserException | SmackParsingException | IOException e) {
             CharSequence content = PacketParserUtils.parseContentDepth(parser,
                             parserDepth);
             UnparseableStanza message = new UnparseableStanza(content, e);
@@ -1295,7 +1303,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
             final IQ iq = (IQ) packet;
             if (iq.isRequestIQ()) {
                 final IQ iqRequest = iq;
-                final String key = XmppStringUtils.generateKey(iq.getChildElementName(), iq.getChildElementNamespace());
+                final QName key = iqRequest.getChildElementQName();
                 IQRequestHandler iqRequestHandler;
                 final IQ.Type type = iq.getType();
                 switch (type) {
@@ -1614,9 +1622,9 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         streamFeatures.clear();
         final int initialDepth = parser.getDepth();
         while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
 
-            if (eventType == XmlPullParser.START_TAG && parser.getDepth() == initialDepth + 1) {
+            if (eventType == XmlPullParser.Event.START_ELEMENT && parser.getDepth() == initialDepth + 1) {
                 FullyQualifiedElement streamFeature = null;
                 String name = parser.getName();
                 String namespace = parser.getNamespace();
@@ -1647,7 +1655,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
                     addStreamFeature(streamFeature);
                 }
             }
-            else if (eventType == XmlPullParser.END_TAG && parser.getDepth() == initialDepth) {
+            else if (eventType == XmlPullParser.Event.END_ELEMENT && parser.getDepth() == initialDepth) {
                 break;
             }
         }
@@ -1686,7 +1694,8 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
     @SuppressWarnings("unchecked")
     @Override
     public <F extends FullyQualifiedElement> F getFeature(String element, String namespace) {
-        return (F) streamFeatures.get(XmppStringUtils.generateKey(element, namespace));
+        QName qname = new QName(namespace, element);
+        return (F) streamFeatures.get(qname);
     }
 
     @Override
@@ -1695,7 +1704,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
     }
 
     protected void addStreamFeature(FullyQualifiedElement feature) {
-        String key = XmppStringUtils.generateKey(feature.getElementName(), feature.getNamespace());
+        QName key = feature.getQName();
         streamFeatures.put(key, feature);
     }
 
@@ -1804,7 +1813,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
 
     @Override
     public IQRequestHandler registerIQRequestHandler(final IQRequestHandler iqRequestHandler) {
-        final String key = XmppStringUtils.generateKey(iqRequestHandler.getElement(), iqRequestHandler.getNamespace());
+        final QName key = iqRequestHandler.getQName();
         switch (iqRequestHandler.getType()) {
         case set:
             synchronized (setIqRequestHandler) {
@@ -1827,7 +1836,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
 
     @Override
     public IQRequestHandler unregisterIQRequestHandler(String element, String namespace, IQ.Type type) {
-        final String key = XmppStringUtils.generateKey(element, namespace);
+        final QName key = new QName(namespace, element);
         switch (type) {
         case set:
             synchronized (setIqRequestHandler) {
@@ -2044,13 +2053,13 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
                 try {
                     Constructor<?> c = Class.forName("sun.security.pkcs11.SunPKCS11").getConstructor(InputStream.class);
                     String pkcs11Config = "name = SmartCard\nlibrary = " + config.getPKCS11Library();
-                    ByteArrayInputStream config = new ByteArrayInputStream(pkcs11Config.getBytes(StringUtils.UTF8));
+                    ByteArrayInputStream config = new ByteArrayInputStream(pkcs11Config.getBytes(StandardCharsets.UTF_8));
                     Provider p = (Provider) c.newInstance(config);
                     Security.addProvider(p);
-                    ks = KeyStore.getInstance("PKCS11",p);
-                    pcb = new PasswordCallback("PKCS11 Password: ",false);
+                    ks = KeyStore.getInstance("PKCS11", p);
+                    pcb = new PasswordCallback("PKCS11 Password: ", false);
                     callbackHandler.handle(new Callback[] {pcb});
-                    ks.load(null,pcb.getPassword());
+                    ks.load(null, pcb.getPassword());
                 }
                 catch (Exception e) {
                     LOGGER.log(Level.WARNING, "Exception", e);
@@ -2058,8 +2067,8 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
                 }
             }
             else if ("Apple".equals(keyStoreType)) {
-                ks = KeyStore.getInstance("KeychainStore","Apple");
-                ks.load(null,null);
+                ks = KeyStore.getInstance("KeychainStore", "Apple");
+                ks.load(null, null);
                 // pcb = new PasswordCallback("Apple Keychain",false);
                 // pcb.setPassword(null);
             }

smack-core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java

@@ -25,6 +25,8 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 import javax.net.SocketFactory;
 import javax.net.ssl.HostnameVerifier;
@@ -46,6 +48,7 @@ import org.jxmpp.jid.impl.JidCreate;
 import org.jxmpp.jid.parts.Resourcepart;
 import org.jxmpp.stringprep.XmppStringprepException;
 import org.minidns.dnsname.DnsName;
+import org.minidns.dnsname.InvalidDnsNameException;
 import org.minidns.util.InetAddressUtil;
 
 /**
@@ -81,6 +84,8 @@ public abstract class ConnectionConfiguration {
         SmackConfiguration.getVersion();
     }
 
+    private static final Logger LOGGER = Logger.getLogger(ConnectionConfiguration.class.getName());
+
     /**
      * The XMPP domain of the XMPP Service. Usually servers use the same service name as the name
      * of the server. However, there are some servers like google where host would be
@@ -88,6 +93,8 @@ public abstract class ConnectionConfiguration {
      */
     protected final DomainBareJid xmppServiceDomain;
 
+    protected final DnsName xmppServiceDomainDnsName;
+
     protected final InetAddress hostAddress;
     protected final DnsName host;
     protected final int port;
@@ -149,7 +156,7 @@ public abstract class ConnectionConfiguration {
 
     private final boolean compressionEnabled;
 
-    protected ConnectionConfiguration(Builder<?,?> builder) {
+    protected ConnectionConfiguration(Builder<?, ?> builder) {
         authzid = builder.authzid;
         username = builder.username;
         password = builder.password;
@@ -162,6 +169,19 @@ public abstract class ConnectionConfiguration {
         if (xmppServiceDomain == null) {
             throw new IllegalArgumentException("Must define the XMPP domain");
         }
+
+        DnsName xmppServiceDomainDnsName;
+        try {
+            xmppServiceDomainDnsName = DnsName.from(xmppServiceDomain);
+        } catch (InvalidDnsNameException e) {
+            LOGGER.log(Level.INFO,
+                            "Could not transform XMPP service domain '" + xmppServiceDomain
+                          + "' to a DNS name. TLS X.509 certificate validiation may not be possible.",
+                            e);
+            xmppServiceDomainDnsName = null;
+        }
+        this.xmppServiceDomainDnsName = xmppServiceDomainDnsName;
+
         hostAddress = builder.hostAddress;
         host = builder.host;
         port = builder.port;
@@ -225,6 +245,17 @@ public abstract class ConnectionConfiguration {
         return xmppServiceDomain;
     }
 
+    /**
+     * Returns the XMPP service domain as DNS name if possible. Note that since not every XMPP address domainpart is a
+     * valid DNS name, this method may return <code>null</code>.
+     *
+     * @return the XMPP service domain as DNS name or <code>null</code>.
+     * @since 4.3.4
+     */
+    public DnsName getXmppServiceDomainAsDnsNameIfPossible() {
+        return xmppServiceDomainDnsName;
+    }
+
     /**
      * Returns the TLS security mode used when making the connection. By default,
      * the mode is {@link SecurityMode#ifpossible}.

smack-core/src/main/java/org/jivesoftware/smack/NonzaCallback.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2018 Florian Schmaus
+ * Copyright 2018-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,18 +19,18 @@ package org.jivesoftware.smack;
 import java.util.HashMap;
 import java.util.Map;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.SmackException.NoResponseException;
 import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.XMPPException.FailedNonzaException;
 import org.jivesoftware.smack.packet.Nonza;
 import org.jivesoftware.smack.util.XmppElementUtil;
 
-import org.jxmpp.util.XmppStringUtils;
-
 public class NonzaCallback {
 
     protected final AbstractXMPPConnection connection;
-    protected final Map<String, GenericElementListener<? extends Nonza>> filterAndListeners;
+    protected final Map<QName, GenericElementListener<? extends Nonza>> filterAndListeners;
 
     private NonzaCallback(Builder builder) {
         this.connection = builder.connection;
@@ -39,7 +39,7 @@ public class NonzaCallback {
     }
 
     void onNonzaReceived(Nonza nonza) {
-        String key = XmppStringUtils.generateKey(nonza.getElementName(), nonza.getNamespace());
+        QName key = nonza.getQName();
         GenericElementListener<? extends Nonza> nonzaListener = filterAndListeners.get(key);
 
         nonzaListener.processElement(nonza);
@@ -47,8 +47,8 @@ public class NonzaCallback {
 
     public void cancel() {
         synchronized (connection.nonzaCallbacks) {
-            for (Map.Entry<String, GenericElementListener<? extends Nonza>> entry : filterAndListeners.entrySet()) {
-                String filterKey = entry.getKey();
+            for (Map.Entry<QName, GenericElementListener<? extends Nonza>> entry : filterAndListeners.entrySet()) {
+                QName filterKey = entry.getKey();
                 NonzaCallback installedCallback = connection.nonzaCallbacks.get(filterKey);
                 if (equals(installedCallback)) {
                     connection.nonzaCallbacks.remove(filterKey);
@@ -63,7 +63,7 @@ public class NonzaCallback {
         }
 
         synchronized (connection.nonzaCallbacks) {
-            for (String key : filterAndListeners.keySet()) {
+            for (QName key : filterAndListeners.keySet()) {
                 connection.nonzaCallbacks.put(key, this);
             }
         }
@@ -78,8 +78,8 @@ public class NonzaCallback {
                         Builder builder) {
             super(builder);
 
-            final String successNonzaKey = XmppElementUtil.getKeyFor(successNonzaClass);
-            final String failedNonzaKey = XmppElementUtil.getKeyFor(failedNonzaClass);
+            final QName successNonzaKey = XmppElementUtil.getQNameFor(successNonzaClass);
+            final QName failedNonzaKey = XmppElementUtil.getQNameFor(failedNonzaClass);
 
             final GenericElementListener<SN> successListener = new GenericElementListener<SN>(successNonzaClass) {
                 @Override
@@ -139,14 +139,14 @@ public class NonzaCallback {
     public static final class Builder {
         private final AbstractXMPPConnection connection;
 
-        private Map<String, GenericElementListener<? extends Nonza>> filterAndListeners = new HashMap<>();
+        private Map<QName, GenericElementListener<? extends Nonza>> filterAndListeners = new HashMap<>();
 
         Builder(AbstractXMPPConnection connection) {
             this.connection = connection;
         }
 
         public <N extends Nonza> Builder listenFor(Class<? extends N> nonza, GenericElementListener<? extends N> nonzaListener) {
-            String key = XmppElementUtil.getKeyFor(nonza);
+            QName key = XmppElementUtil.getQNameFor(nonza);
             filterAndListeners.put(key, nonzaListener);
             return this;
         }

smack-core/src/main/java/org/jivesoftware/smack/SmackConfiguration.java

@@ -29,6 +29,7 @@ import javax.net.ssl.HostnameVerifier;
 import org.jivesoftware.smack.compression.XMPPInputOutputStream;
 import org.jivesoftware.smack.debugger.ReflectionDebuggerFactory;
 import org.jivesoftware.smack.debugger.SmackDebuggerFactory;
+import org.jivesoftware.smack.parsing.ExceptionThrowingCallback;
 import org.jivesoftware.smack.parsing.ExceptionThrowingCallbackWithHint;
 import org.jivesoftware.smack.parsing.ParsingExceptionCallback;
 import org.jivesoftware.smack.util.Objects;
@@ -380,4 +381,5 @@ public final class SmackConfiguration {
     public static int getDefaultConcurrencyLevelLimit() {
         return defaultConcurrencyLevelLimit;
     }
+
 }

smack-core/src/main/java/org/jivesoftware/smack/SmackInitialization.java

@@ -20,6 +20,7 @@ package org.jivesoftware.smack;
 import java.io.BufferedReader;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.Collection;
 import java.util.List;
 import java.util.logging.Level;
@@ -44,10 +45,9 @@ import org.jivesoftware.smack.sasl.core.SCRAMSHA1Mechanism;
 import org.jivesoftware.smack.sasl.core.ScramSha1PlusMechanism;
 import org.jivesoftware.smack.util.CloseableUtil;
 import org.jivesoftware.smack.util.FileUtils;
-import org.jivesoftware.smack.util.StringUtils;
+import org.jivesoftware.smack.util.PacketParserUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserFactory;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 
 public final class SmackInitialization {
@@ -69,7 +69,7 @@ public final class SmackInitialization {
         String smackVersion;
         BufferedReader reader = null;
         try {
-            reader = new BufferedReader(new InputStreamReader(FileUtils.getStreamForClasspathFile("org.jivesoftware.smack/version", null), StringUtils.UTF8));
+            reader = new BufferedReader(new InputStreamReader(FileUtils.getStreamForClasspathFile("org.jivesoftware.smack/version", null), StandardCharsets.UTF_8));
             smackVersion = reader.readLine();
         } catch (Exception e) {
             LOGGER.log(Level.SEVERE, "Could not determine Smack version", e);
@@ -141,12 +141,10 @@ public final class SmackInitialization {
 
     public static void processConfigFile(InputStream cfgFileStream,
                     Collection<Exception> exceptions, ClassLoader classLoader) throws Exception {
-        XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
-        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
-        parser.setInput(cfgFileStream, "UTF-8");
-        int eventType = parser.getEventType();
+        XmlPullParser parser = PacketParserUtils.getParserFor(cfgFileStream);
+        XmlPullParser.Event eventType = parser.getEventType();
         do {
-            if (eventType == XmlPullParser.START_TAG) {
+            if (eventType == XmlPullParser.Event.START_ELEMENT) {
                 if (parser.getName().equals("startupClasses")) {
                     parseClassesToLoad(parser, false, exceptions, classLoader);
                 }
@@ -156,7 +154,7 @@ public final class SmackInitialization {
             }
             eventType = parser.next();
         }
-        while (eventType != XmlPullParser.END_DOCUMENT);
+        while (eventType != XmlPullParser.Event.END_DOCUMENT);
         CloseableUtil.maybeClose(cfgFileStream, LOGGER);
     }
 
@@ -164,12 +162,10 @@ public final class SmackInitialization {
                     Collection<Exception> exceptions, ClassLoader classLoader)
                     throws Exception {
         final String startName = parser.getName();
-        int eventType;
-        String name;
+        XmlPullParser.Event eventType;
         outerloop: do {
             eventType = parser.next();
-            name = parser.getName();
-            if (eventType == XmlPullParser.START_TAG && "className".equals(name)) {
+            if (eventType == XmlPullParser.Event.START_ELEMENT && "className".equals(parser.getName())) {
                 String classToLoad = parser.nextText();
                 if (SmackConfiguration.isDisabledSmackClass(classToLoad)) {
                     continue outerloop;
@@ -188,7 +184,7 @@ public final class SmackInitialization {
                 }
             }
         }
-        while (!(eventType == XmlPullParser.END_TAG && startName.equals(name)));
+        while (!(eventType == XmlPullParser.Event.END_ELEMENT && startName.equals(parser.getName())));
     }
 
     private static void loadSmackClass(String className, boolean optional, ClassLoader classLoader) throws Exception {

smack-core/src/main/java/org/jivesoftware/smack/SmackReactor.java

@@ -149,9 +149,8 @@ public class SmackReactor {
         long releaseTimeEpoch = System.currentTimeMillis() + unit.toMillis(delay);
         Date releaseTimeDate = new Date(releaseTimeEpoch);
         ScheduledAction scheduledAction = new ScheduledAction(runnable, releaseTimeDate, this);
-        synchronized (scheduledActions) {
-            scheduledActions.add(scheduledAction);
-        }
+        scheduledActions.add(scheduledAction);
+        selector.wakeup();
         return scheduledAction;
     }
 
@@ -209,7 +208,8 @@ public class SmackReactor {
 
             long selectWait;
             if (nextScheduledAction == null) {
-                // There is no next scheduled action, wait indefinitely in select().
+                // There is no next scheduled action, wait indefinitely in select() or until another thread invokes
+                // selector.wakeup().
                 selectWait = 0;
             } else {
                 selectWait = nextScheduledAction.getTimeToDueMillis();

smack-core/src/main/java/org/jivesoftware/smack/StanzaCollector.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2003-2007 Jive Software, 2016-2018 Florian Schmaus.
+ * Copyright 2003-2007 Jive Software, 2016-2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,7 +41,7 @@ import org.jivesoftware.smack.packet.Stanza;
  * @see XMPPConnection#createStanzaCollector(StanzaFilter)
  * @author Matt Tucker
  */
-public class StanzaCollector implements AutoCloseable {
+public final class StanzaCollector implements AutoCloseable {
 
     private final StanzaFilter packetFilter;
 
@@ -69,7 +69,7 @@ public class StanzaCollector implements AutoCloseable {
      * @param connection the connection the collector is tied to.
      * @param configuration the configuration used to construct this collector
      */
-    protected StanzaCollector(XMPPConnection connection, Configuration configuration) {
+    StanzaCollector(XMPPConnection connection, Configuration configuration) {
         this.connection = connection;
         this.packetFilter = configuration.packetFilter;
         this.resultQueue = new ArrayDeque<>(configuration.size);
@@ -98,18 +98,6 @@ public class StanzaCollector implements AutoCloseable {
         }
     }
 
-    /**
-     * Returns the stanza filter associated with this stanza collector. The packet
-     * filter is used to determine what packets are queued as results.
-     *
-     * @return the stanza filter.
-     * @deprecated use {@link #getStanzaFilter()} instead.
-     */
-    @Deprecated
-    public StanzaFilter getPacketFilter() {
-        return getStanzaFilter();
-    }
-
     /**
      * Returns the stanza filter associated with this stanza collector. The stanza
      * filter is used to determine what stanzas are queued as results.
@@ -329,6 +317,21 @@ public class StanzaCollector implements AutoCloseable {
         return resultQueue.size();
     }
 
+    private String stringCache;
+
+    @Override
+    public String toString() {
+        if (stringCache == null) {
+            StringBuilder sb = new StringBuilder(128);
+            sb.append("Stanza Collector filter='").append(packetFilter).append('\'');
+            if (request != null) {
+                sb.append(" request='").append(request).append('\'');
+            }
+            stringCache = sb.toString();
+        }
+        return stringCache;
+    }
+
     synchronized void notifyConnectionError(Exception exception) {
         connectionException = exception;
         notifyAll();
@@ -380,19 +383,6 @@ public class StanzaCollector implements AutoCloseable {
         private Configuration() {
         }
 
-        /**
-         * Set the stanza filter used by this collector. If <code>null</code>, then all packets will
-         * get collected by this collector.
-         *
-         * @param packetFilter
-         * @return a reference to this configuration.
-         * @deprecated use {@link #setStanzaFilter(StanzaFilter)} instead.
-         */
-        @Deprecated
-        public Configuration setPacketFilter(StanzaFilter packetFilter) {
-            return setStanzaFilter(packetFilter);
-        }
-
         /**
          * Set the stanza filter used by this collector. If <code>null</code>, then all stanzas will
          * get collected by this collector.

smack-core/src/main/java/org/jivesoftware/smack/compress/provider/CompressedProvider.java

@@ -20,7 +20,7 @@ import org.jivesoftware.smack.compress.packet.Compressed;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.provider.NonzaProvider;
 
-import org.xmlpull.v1.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 public final class CompressedProvider extends NonzaProvider<Compressed> {
 

smack-core/src/main/java/org/jivesoftware/smack/compress/provider/FailureProvider.java

@@ -27,8 +27,8 @@ import org.jivesoftware.smack.parsing.SmackParsingException;
 import org.jivesoftware.smack.provider.NonzaProvider;
 import org.jivesoftware.smack.util.PacketParserUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 public final class FailureProvider extends NonzaProvider<Failure> {
 
@@ -46,9 +46,9 @@ public final class FailureProvider extends NonzaProvider<Failure> {
         XmlEnvironment failureXmlEnvironment = XmlEnvironment.from(parser, xmlEnvironment);
 
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 String namespace = parser.getNamespace();
                 switch (namespace) {
@@ -72,11 +72,12 @@ public final class FailureProvider extends NonzaProvider<Failure> {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default: // fall out
             }
         }
 

smack-core/src/main/java/org/jivesoftware/smack/datatypes/Scalar.java

@@ -0,0 +1,70 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.datatypes;
+
+public abstract class Scalar extends java.lang.Number {
+
+    /**
+     *
+     */
+    private static final long serialVersionUID = 1L;
+
+    private final java.lang.Number number;
+
+    protected Scalar(java.lang.Number number) {
+        this.number = number;
+    }
+
+    public final Number number() {
+        return number;
+    }
+
+    @Override
+    public final int intValue() {
+        return number.intValue();
+    }
+
+    @Override
+    public final long longValue() {
+        return number.longValue();
+    }
+
+    @Override
+    public final float floatValue() {
+        return number.floatValue();
+    }
+
+    @Override
+    public final double doubleValue() {
+        return number.doubleValue();
+    }
+
+    @Override
+    public final int hashCode() {
+        return number.hashCode();
+    }
+
+    @Override
+    public final boolean equals(Object other) {
+        return number.equals(other);
+    }
+
+    @Override
+    public final String toString() {
+        return number.toString();
+    }
+}

smack-core/src/main/java/org/jivesoftware/smack/datatypes/UInt16.java

@@ -0,0 +1,42 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.datatypes;
+
+import org.jivesoftware.smack.util.NumberUtil;
+
+/**
+ * A number representing an unsigned 16-bit integer. Can be used for values with the XML schema type "xs:unsingedShort".
+ */
+public final class UInt16 extends Scalar {
+
+    private static final long serialVersionUID = 1L;
+
+    private final int number;
+
+    private UInt16(int number) {
+        super(NumberUtil.requireUShort16(number));
+        this.number = number;
+    }
+
+    public int nativeRepresentation() {
+        return number;
+    }
+
+    public static UInt16 from(int number) {
+        return new UInt16(number);
+    }
+}

smack-core/src/main/java/org/jivesoftware/smack/datatypes/UInt32.java

@@ -0,0 +1,42 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.datatypes;
+
+import org.jivesoftware.smack.util.NumberUtil;
+
+/**
+ * A number representing an unsigned 32-bit integer. Can be used for values with the XML schema type "xs:unsignedInt".
+ */
+public final class UInt32 extends Scalar {
+
+    private static final long serialVersionUID = 1L;
+
+    private final long number;
+
+    private UInt32(long number) {
+        super(NumberUtil.requireUInt32(number));
+        this.number = number;
+    }
+
+    public long nativeRepresentation() {
+        return number;
+    }
+
+    public static UInt32 from(long number) {
+        return new UInt32(number);
+    }
+}

smack-core/src/main/java/org/jivesoftware/smack/datatypes/package-info.java

@@ -0,0 +1,21 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Custom datatypes for Integers.
+ */
+package org.jivesoftware.smack.datatypes;

smack-core/src/main/java/org/jivesoftware/smack/fsm/AbstractXmppStateMachineConnection.java

@@ -57,10 +57,10 @@ import org.jivesoftware.smack.sasl.packet.SaslStreamElements.Challenge;
 import org.jivesoftware.smack.sasl.packet.SaslStreamElements.Success;
 import org.jivesoftware.smack.util.Objects;
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jxmpp.jid.parts.Resourcepart;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
 
 public abstract class AbstractXmppStateMachineConnection extends AbstractXMPPConnection {
 
@@ -310,10 +310,10 @@ public abstract class AbstractXmppStateMachineConnection extends AbstractXMPPCon
         // Skip the enclosing stream open what is guaranteed to be there.
         parser.next();
 
-        int event = parser.getEventType();
+        XmlPullParser.Event event = parser.getEventType();
         outerloop: while (true) {
             switch (event) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 final String name = parser.getName();
                 // Note that we don't handle "stream" here as it's done in the splitter.
                 switch (name) {
@@ -353,8 +353,9 @@ public abstract class AbstractXmppStateMachineConnection extends AbstractXMPPCon
                     break;
                 }
                 break;
-            case XmlPullParser.END_DOCUMENT:
+            case END_DOCUMENT:
                 break outerloop;
+            default: // fall out
             }
             event = parser.next();
         }

smack-core/src/main/java/org/jivesoftware/smack/iqrequest/IQRequestHandler.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2015 Florian Schmaus
+ * Copyright 2015-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
  */
 package org.jivesoftware.smack.iqrequest;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.packet.IQ;
 
 /**
@@ -50,4 +52,8 @@ public interface IQRequestHandler {
     String getElement();
 
     String getNamespace();
+
+    default QName getQName() {
+        return new QName(getNamespace(), getElement());
+    }
 }

smack-core/src/main/java/org/jivesoftware/smack/packet/DefaultExtensionElement.java

@@ -52,7 +52,7 @@ public class DefaultExtensionElement implements ExtensionElement {
 
     private String elementName;
     private String namespace;
-    private Map<String,String> map;
+    private Map<String, String> map;
 
     /**
      * Creates a new generic stanza extension.
@@ -107,7 +107,7 @@ public class DefaultExtensionElement implements ExtensionElement {
         if (map == null) {
             return Collections.emptySet();
         }
-        return Collections.unmodifiableSet(new HashMap<String,String>(map).keySet());
+        return Collections.unmodifiableSet(new HashMap<String, String>(map).keySet());
     }
 
     /**
@@ -131,7 +131,7 @@ public class DefaultExtensionElement implements ExtensionElement {
      */
     public synchronized void setValue(String name, String value) {
         if (map == null) {
-            map = new HashMap<String,String>();
+            map = new HashMap<String, String>();
         }
         map.put(name, value);
     }

smack-core/src/main/java/org/jivesoftware/smack/packet/FullyQualifiedElement.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2018 Florian Schmaus
+ * Copyright 2018-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
  */
 package org.jivesoftware.smack.packet;
 
+import javax.xml.namespace.QName;
+
 public interface FullyQualifiedElement extends NamedElement {
 
     /**
@@ -25,4 +27,9 @@ public interface FullyQualifiedElement extends NamedElement {
      */
     String getNamespace();
 
+    default QName getQName() {
+        String namespaceURI = getNamespace();
+        String localPart = getElementName();
+        return new QName(namespaceURI, localPart);
+    }
 }

smack-core/src/main/java/org/jivesoftware/smack/packet/IQ.java

@@ -20,6 +20,8 @@ package org.jivesoftware.smack.packet;
 import java.util.List;
 import java.util.Locale;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.util.Objects;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
@@ -46,6 +48,7 @@ public abstract class IQ extends Stanza {
     public static final String IQ_ELEMENT = "iq";
     public static final String QUERY_ELEMENT = "query";
 
+    private final QName childElementQName;
     private final String childElementName;
     private final String childElementNamespace;
 
@@ -56,6 +59,7 @@ public abstract class IQ extends Stanza {
         type = iq.getType();
         this.childElementName = iq.childElementName;
         this.childElementNamespace = iq.childElementNamespace;
+        this.childElementQName = iq.childElementQName;
     }
 
     protected IQ(String childElementName) {
@@ -65,6 +69,11 @@ public abstract class IQ extends Stanza {
     protected IQ(String childElementName, String childElementNamespace) {
         this.childElementName = childElementName;
         this.childElementNamespace = childElementNamespace;
+        if (childElementName == null) {
+            childElementQName = null;
+        } else {
+            childElementQName = new QName(childElementNamespace, childElementName);
+        }
     }
 
     /**
@@ -115,6 +124,10 @@ public abstract class IQ extends Stanza {
         return !isRequestIQ();
     }
 
+    public final QName getChildElementQName() {
+        return childElementQName;
+    }
+
     public final String getChildElementName() {
         return childElementName;
     }

smack-core/src/main/java/org/jivesoftware/smack/packet/Message.java

@@ -24,6 +24,8 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Set;
 
+import org.jivesoftware.smack.util.EqualsUtil;
+import org.jivesoftware.smack.util.HashCode;
 import org.jivesoftware.smack.util.Objects;
 import org.jivesoftware.smack.util.TypedCloneable;
 import org.jivesoftware.smack.util.XmlStringBuilder;
@@ -561,32 +563,22 @@ public final class Message extends Stanza implements TypedCloneable<Message> {
             return subject;
         }
 
+        private final HashCode.Cache hashCodeCache = new HashCode.Cache();
 
         @Override
         public int hashCode() {
-            final int prime = 31;
-            int result = 1;
-            if (language != null) {
-                result = prime * result + this.language.hashCode();
-            }
-            result = prime * result + this.subject.hashCode();
-            return result;
+            return hashCodeCache.getHashCode(c ->
+                c.append(language)
+                 .append(subject)
+            );
         }
 
         @Override
         public boolean equals(Object obj) {
-            if (this == obj) {
-                return true;
-            }
-            if (obj == null) {
-                return false;
-            }
-            if (getClass() != obj.getClass()) {
-                return false;
-            }
-            Subject other = (Subject) obj;
-            // simplified comparison because language and subject are always set
-            return this.language.equals(other.language) && this.subject.equals(other.subject);
+            return EqualsUtil.equals(this, obj, (e, o) ->
+                e.append(language, o.language)
+                 .append(subject, o.subject)
+            );
         }
 
         @Override
@@ -670,31 +662,22 @@ public final class Message extends Stanza implements TypedCloneable<Message> {
             return message;
         }
 
+        private final HashCode.Cache hashCodeCache = new HashCode.Cache();
+
         @Override
         public int hashCode() {
-            final int prime = 31;
-            int result = 1;
-            if (language != null) {
-                result = prime * result + this.language.hashCode();
-            }
-            result = prime * result + this.message.hashCode();
-            return result;
+            return hashCodeCache.getHashCode(c ->
+                c.append(language)
+                .append(message)
+            );
         }
 
         @Override
         public boolean equals(Object obj) {
-            if (this == obj) {
-                return true;
-            }
-            if (obj == null) {
-                return false;
-            }
-            if (getClass() != obj.getClass()) {
-                return false;
-            }
-            Body other = (Body) obj;
-            // simplified comparison because language and message are always set
-            return Objects.equals(this.language, other.language) && this.message.equals(other.message);
+            return EqualsUtil.equals(this, obj, (e, o) ->
+                e.append(language, o.language)
+                 .append(message, o.message)
+            );
         }
 
         @Override

smack-core/src/main/java/org/jivesoftware/smack/packet/Packet.java

@@ -150,7 +150,7 @@ public interface Packet extends TopLevelStreamElement {
     /**
      * Returns the first extension of this stanza that has the given namespace.
      * <p>
-     * When possible, use {@link #getExtension(String,String)} instead.
+     * When possible, use {@link #getExtension(String, String)} instead.
      * </p>
      *
      * @param namespace the namespace of the extension that is desired.

smack-core/src/main/java/org/jivesoftware/smack/packet/Presence.java

@@ -68,12 +68,12 @@ public final class Presence extends Stanza implements TypedCloneable<Presence> {
     private String status = null;
 
     /**
-     * The priority of the presence. The magic value {@link Integer#MIN_VALUE} is used to indicate that the original
+     * The priority of the presence. It is <code>null</code> to indicate that the original
      * presence stanza did not had an explicit priority set. In which case the priority defaults to 0.
      *
      * @see <a href="https://tools.ietf.org/html/rfc6121#section-4.7.2.3">RFC 6121 § 4.7.2.3.</a>
      */
-    private int priority = Integer.MIN_VALUE;
+    private Byte priority;
 
     private Mode mode = null;
 
@@ -203,13 +203,13 @@ public final class Presence extends Stanza implements TypedCloneable<Presence> {
     }
 
     /**
-     * Returns the priority of the presence, or Integer.MIN_VALUE if no priority has been set.
+     * Returns the priority of the presence.
      *
      * @return the priority.
      * @see <a href="https://tools.ietf.org/html/rfc6121#section-4.7.2.3">RFC 6121 § 4.7.2.3. Priority Element</a>
      */
     public int getPriority() {
-        if (priority == Integer.MIN_VALUE) {
+        if (priority == null) {
             return 0;
         }
         return priority;
@@ -227,6 +227,10 @@ public final class Presence extends Stanza implements TypedCloneable<Presence> {
             throw new IllegalArgumentException("Priority value " + priority +
                     " is not valid. Valid range is -128 through 127.");
         }
+        setPriority((byte) priority);
+    }
+
+    public void setPriority(byte priority) {
         this.priority = priority;
     }
 
@@ -264,7 +268,7 @@ public final class Presence extends Stanza implements TypedCloneable<Presence> {
         if (!StringUtils.isNullOrEmpty(status)) {
             sb.append("status=").append(status).append(',');
         }
-        if (priority != Integer.MIN_VALUE) {
+        if (priority != null) {
             sb.append("prio=").append(priority).append(',');
         }
         sb.append(']');
@@ -282,9 +286,7 @@ public final class Presence extends Stanza implements TypedCloneable<Presence> {
         buf.rightAngleBracket();
 
         buf.optElement("status", status);
-        if (priority != Integer.MIN_VALUE) {
-            buf.element("priority", Integer.toString(priority));
-        }
+        buf.optElement("priority", priority);
         if (mode != null && mode != Mode.available) {
             buf.element("show", mode);
         }

smack-core/src/main/java/org/jivesoftware/smack/packet/StandardExtensionElement.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2015 Florian Schmaus.
+ * Copyright 2015-2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,13 +21,13 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.util.MultiMap;
 import org.jivesoftware.smack.util.Objects;
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
-import org.jxmpp.util.XmppStringUtils;
-
 /**
  * An {@link ExtensionElement} modeling the often required and used XML features when using XMPP. It
  * is therefore suitable for most use cases. Use
@@ -47,7 +47,7 @@ public final class StandardExtensionElement implements ExtensionElement {
     private final String namespace;
     private final Map<String, String> attributes;
     private final String text;
-    private final MultiMap<String, StandardExtensionElement> elements;
+    private final MultiMap<QName, StandardExtensionElement> elements;
 
     private XmlStringBuilder xmlCache;
 
@@ -65,7 +65,7 @@ public final class StandardExtensionElement implements ExtensionElement {
     }
 
     private StandardExtensionElement(String name, String namespace, Map<String, String> attributes, String text,
-                    MultiMap<String, StandardExtensionElement> elements) {
+                    MultiMap<QName, StandardExtensionElement> elements) {
         this.name = StringUtils.requireNotNullNorEmpty(name, "Name must not be null nor empty");
         this.namespace = StringUtils.requireNotNullNorEmpty(namespace, "Namespace must not be null nor empty");
         if (attributes == null) {
@@ -100,7 +100,7 @@ public final class StandardExtensionElement implements ExtensionElement {
         if (elements == null) {
             return null;
         }
-        String key = XmppStringUtils.generateKey(element, namespace);
+        QName key = new QName(namespace, element);
         return elements.getFirst(key);
     }
 
@@ -112,7 +112,7 @@ public final class StandardExtensionElement implements ExtensionElement {
         if (elements == null) {
             return null;
         }
-        String key = XmppStringUtils.generateKey(element, namespace);
+        QName key = new QName(namespace, element);
         return elements.getAll(key);
     }
 
@@ -145,7 +145,7 @@ public final class StandardExtensionElement implements ExtensionElement {
         xml.optEscape(text);
 
         if (elements != null) {
-            for (Map.Entry<String, StandardExtensionElement> entry : elements.entrySet()) {
+            for (Map.Entry<QName, StandardExtensionElement> entry : elements.entrySet()) {
                 xml.append(entry.getValue().toXML(getNamespace()));
             }
         }
@@ -165,7 +165,7 @@ public final class StandardExtensionElement implements ExtensionElement {
 
         private Map<String, String> attributes;
         private String text;
-        private MultiMap<String, StandardExtensionElement> elements;
+        private MultiMap<QName, StandardExtensionElement> elements;
 
         private Builder(String name, String namespace) {
             this.name = name;
@@ -200,7 +200,8 @@ public final class StandardExtensionElement implements ExtensionElement {
             if (elements == null) {
                 elements = new MultiMap<>();
             }
-            String key = XmppStringUtils.generateKey(element.getElementName(), element.getNamespace());
+
+            QName key = element.getQName();
             elements.put(key, element);
             return this;
         }

smack-core/src/main/java/org/jivesoftware/smack/packet/Stanza.java

@@ -23,6 +23,8 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.packet.id.StanzaIdUtil;
 import org.jivesoftware.smack.util.MultiMap;
 import org.jivesoftware.smack.util.PacketUtil;
@@ -31,7 +33,6 @@ import org.jivesoftware.smack.util.XmlStringBuilder;
 import org.jxmpp.jid.Jid;
 import org.jxmpp.jid.impl.JidCreate;
 import org.jxmpp.stringprep.XmppStringprepException;
-import org.jxmpp.util.XmppStringUtils;
 
 /**
  * Base class for XMPP Stanzas, which are called Stanza in older versions of Smack (i.e. < 4.1).
@@ -56,7 +57,7 @@ public abstract class Stanza implements TopLevelStreamElement {
     protected static final String DEFAULT_LANGUAGE =
             java.util.Locale.getDefault().getLanguage().toLowerCase(Locale.US);
 
-    private final MultiMap<String, ExtensionElement> packetExtensions = new MultiMap<>();
+    private final MultiMap<QName, ExtensionElement> extensionElements = new MultiMap<>();
 
     private String id = null;
     private Jid to;
@@ -306,9 +307,9 @@ public abstract class Stanza implements TopLevelStreamElement {
      * @return a list of all extension elements of this stanza.
      */
     public List<ExtensionElement> getExtensions() {
-        synchronized (packetExtensions) {
+        synchronized (extensionElements) {
             // No need to create a new list, values() will already create a new one for us
-            return packetExtensions.values();
+            return extensionElements.values();
         }
     }
 
@@ -326,14 +327,14 @@ public abstract class Stanza implements TopLevelStreamElement {
     public List<ExtensionElement> getExtensions(String elementName, String namespace) {
         requireNotNullNorEmpty(elementName, "elementName must not be null nor empty");
         requireNotNullNorEmpty(namespace, "namespace must not be null nor empty");
-        String key = XmppStringUtils.generateKey(elementName, namespace);
-        return packetExtensions.getAll(key);
+        QName key = new QName(namespace, elementName);
+        return extensionElements.getAll(key);
     }
 
     /**
      * Returns the first extension of this stanza that has the given namespace.
      * <p>
-     * When possible, use {@link #getExtension(String,String)} instead.
+     * When possible, use {@link #getExtension(String, String)} instead.
      * </p>
      *
      * @param namespace the namespace of the extension that is desired.
@@ -359,10 +360,10 @@ public abstract class Stanza implements TopLevelStreamElement {
         if (namespace == null) {
             return null;
         }
-        String key = XmppStringUtils.generateKey(elementName, namespace);
+        QName key = new QName(namespace, elementName);
         ExtensionElement packetExtension;
-        synchronized (packetExtensions) {
-            packetExtension = packetExtensions.getFirst(key);
+        synchronized (extensionElements) {
+            packetExtension = extensionElements.getFirst(key);
         }
         if (packetExtension == null) {
             return null;
@@ -377,9 +378,9 @@ public abstract class Stanza implements TopLevelStreamElement {
      */
     public void addExtension(ExtensionElement extension) {
         if (extension == null) return;
-        String key = XmppStringUtils.generateKey(extension.getElementName(), extension.getNamespace());
-        synchronized (packetExtensions) {
-            packetExtensions.put(key, extension);
+        QName key = extension.getQName();
+        synchronized (extensionElements) {
+            extensionElements.put(key, extension);
         }
     }
 
@@ -393,7 +394,7 @@ public abstract class Stanza implements TopLevelStreamElement {
      */
     public ExtensionElement overrideExtension(ExtensionElement extension) {
         if (extension == null) return null;
-        synchronized (packetExtensions) {
+        synchronized (extensionElements) {
             // Note that we need to use removeExtension(String, String) here. If would use
             // removeExtension(ExtensionElement) then we would remove based on the equality of ExtensionElement, which
             // is not what we want in this case.
@@ -429,9 +430,9 @@ public abstract class Stanza implements TopLevelStreamElement {
         if (elementName == null) {
             return hasExtension(namespace);
         }
-        String key = XmppStringUtils.generateKey(elementName, namespace);
-        synchronized (packetExtensions) {
-            return packetExtensions.containsKey(key);
+        QName key = new QName(namespace, elementName);
+        synchronized (extensionElements) {
+            return extensionElements.containsKey(key);
         }
     }
 
@@ -442,8 +443,8 @@ public abstract class Stanza implements TopLevelStreamElement {
      * @return true if a stanza extension exists, false otherwise.
      */
     public boolean hasExtension(String namespace) {
-        synchronized (packetExtensions) {
-            for (ExtensionElement packetExtension : packetExtensions.values()) {
+        synchronized (extensionElements) {
+            for (ExtensionElement packetExtension : extensionElements.values()) {
                 if (packetExtension.getNamespace().equals(namespace)) {
                     return true;
                 }
@@ -460,9 +461,9 @@ public abstract class Stanza implements TopLevelStreamElement {
      * @return the removed stanza extension or null.
      */
     public ExtensionElement removeExtension(String elementName, String namespace) {
-        String key = XmppStringUtils.generateKey(elementName, namespace);
-        synchronized (packetExtensions) {
-            return packetExtensions.remove(key);
+        QName key = new QName(namespace, elementName);
+        synchronized (extensionElements) {
+            return extensionElements.remove(key);
         }
     }
 
@@ -473,9 +474,9 @@ public abstract class Stanza implements TopLevelStreamElement {
      * @return the removed stanza extension or null.
      */
     public ExtensionElement removeExtension(ExtensionElement extension)  {
-        String key = XmppStringUtils.generateKey(extension.getElementName(), extension.getNamespace());
-        synchronized (packetExtensions) {
-            List<ExtensionElement> list = packetExtensions.getAll(key);
+        QName key = extension.getQName();
+        synchronized (extensionElements) {
+            List<ExtensionElement> list = extensionElements.getAll(key);
             boolean removed = list.remove(extension);
             if (removed) {
                 return extension;

smack-core/src/main/java/org/jivesoftware/smack/packet/XmlEnvironment.java

@@ -19,7 +19,7 @@ package org.jivesoftware.smack.packet;
 import org.jivesoftware.smack.util.ParserUtils;
 import org.jivesoftware.smack.util.StringUtils;
 
-import org.xmlpull.v1.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 public class XmlEnvironment {
 

smack-core/src/main/java/org/jivesoftware/smack/parsing/StandardExtensionElementProvider.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2015 Florian Schmaus.
+ * Copyright 2015-2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,8 +26,8 @@ import org.jivesoftware.smack.provider.ExtensionElementProvider;
 import org.jivesoftware.smack.util.ParserUtils;
 import org.jivesoftware.smack.util.StringUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 /**
  * The parser for {@link StandardExtensionElement}s.
@@ -47,7 +47,7 @@ public class StandardExtensionElementProvider extends ExtensionElementProvider<S
         String name = parser.getName();
         String namespace = parser.getNamespace();
         StandardExtensionElement.Builder builder = StandardExtensionElement.builder(name, namespace);
-        final int namespaceCount = parser.getNamespaceCount(initialDepth);
+        final int namespaceCount = parser.getNamespaceCount();
         final int attributeCount = parser.getAttributeCount();
         final Map<String, String> attributes = new LinkedHashMap<>(namespaceCount + attributeCount);
         for (int i = 0; i < namespaceCount; i++) {
@@ -77,19 +77,22 @@ public class StandardExtensionElementProvider extends ExtensionElementProvider<S
         builder.addAttributes(attributes);
 
         outerloop: while (true) {
-            int event = parser.next();
+            XmlPullParser.Event event = parser.next();
             switch (event) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 builder.addElement(parse(parser, parser.getDepth(), xmlEnvironment));
                 break;
-            case XmlPullParser.TEXT:
+            case TEXT_CHARACTERS:
                 builder.setText(parser.getText());
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (initialDepth == parser.getDepth()) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
 

smack-core/src/main/java/org/jivesoftware/smack/provider/BindIQProvider.java

@@ -20,12 +20,12 @@ import java.io.IOException;
 
 import org.jivesoftware.smack.packet.Bind;
 import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jxmpp.jid.EntityFullJid;
 import org.jxmpp.jid.impl.JidCreate;
 import org.jxmpp.jid.parts.Resourcepart;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
 
 public class BindIQProvider extends IQProvider<Bind> {
 
@@ -34,9 +34,9 @@ public class BindIQProvider extends IQProvider<Bind> {
         String name;
         Bind bind = null;
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 name = parser.getName();
                 switch (name) {
                 case "resource":
@@ -49,11 +49,14 @@ public class BindIQProvider extends IQProvider<Bind> {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         return bind;

smack-core/src/main/java/org/jivesoftware/smack/provider/BodyElementProvider.java

@@ -24,8 +24,8 @@ import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.util.ParserUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 public class BodyElementProvider extends ExtensionElementProvider<Message.Body> {
 

smack-core/src/main/java/org/jivesoftware/smack/provider/EmbeddedExtensionProvider.java

@@ -27,8 +27,8 @@ import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.parsing.SmackParsingException;
 import org.jivesoftware.smack.util.PacketParserUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 /**
  *
@@ -97,14 +97,14 @@ public abstract class EmbeddedExtensionProvider<PE extends ExtensionElement> ext
         }
 
         List<ExtensionElement> extensions = new ArrayList<>();
-        int event;
+        XmlPullParser.Event event;
         do {
             event = parser.next();
 
-            if (event == XmlPullParser.START_TAG)
+            if (event == XmlPullParser.Event.START_ELEMENT)
                 PacketParserUtils.addExtensionElement(extensions, parser, xmlEnvironment);
         }
-        while (!(event == XmlPullParser.END_TAG && parser.getDepth() == initialDepth));
+        while (!(event == XmlPullParser.Event.END_ELEMENT && parser.getDepth() == initialDepth));
 
         return createReturnExtension(name, namespace, attMap, extensions);
     }

smack-core/src/main/java/org/jivesoftware/smack/provider/IntrospectionProvider.java

@@ -24,8 +24,8 @@ import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.util.ParserUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 public class IntrospectionProvider{
 
@@ -81,9 +81,9 @@ public class IntrospectionProvider{
         ParserUtils.assertAtStartTag(parser);
         Object object = objectClass.getConstructor().newInstance();
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 String stringValue = parser.nextText();
                 Class<?> propertyType = object.getClass().getMethod(
@@ -97,11 +97,14 @@ public class IntrospectionProvider{
                                 propertyType).invoke(object, value);
                 break;
 
-            case  XmlPullParser.END_TAG:
+            case  END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         ParserUtils.assertAtEndTag(parser);

smack-core/src/main/java/org/jivesoftware/smack/provider/Provider.java

@@ -26,8 +26,8 @@ import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.parsing.SmackParsingException;
 import org.jivesoftware.smack.util.ParserUtils;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 /**
  * Smack provider are the parsers used to deserialize raw XMPP into the according Java {@link Element}s.

smack-core/src/main/java/org/jivesoftware/smack/provider/ProviderFileLoader.java

@@ -26,9 +26,8 @@ import java.util.logging.Logger;
 
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.IQ;
-
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserFactory;
+import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 /**
  * Loads the {@link IQProvider} and {@link ExtensionElementProvider} information from a standard provider file in preparation
@@ -54,12 +53,10 @@ public class ProviderFileLoader implements ProviderLoader {
     public ProviderFileLoader(InputStream providerStream, ClassLoader classLoader) {
         // Load processing providers.
         try (InputStream is = providerStream) {
-            XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
-            parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
-            parser.setInput(is, "UTF-8");
-            int eventType = parser.getEventType();
+            XmlPullParser parser = PacketParserUtils.getParserFor(is);
+            XmlPullParser.Event eventType = parser.getEventType();
             do {
-                if (eventType == XmlPullParser.START_TAG) {
+                if (eventType == XmlPullParser.Event.START_ELEMENT) {
                     final String typeName = parser.getName();
 
                     try {
@@ -134,7 +131,7 @@ public class ProviderFileLoader implements ProviderLoader {
                 }
                 eventType = parser.next();
             }
-            while (eventType != XmlPullParser.END_DOCUMENT);
+            while (eventType != XmlPullParser.Event.END_DOCUMENT);
         }
         catch (Exception e) {
             LOGGER.log(Level.SEVERE, "Unknown error occurred while parsing provider file", e);

smack-core/src/main/java/org/jivesoftware/smack/provider/ProviderManager.java

@@ -22,6 +22,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.SmackConfiguration;
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.IQ;
@@ -29,8 +31,6 @@ import org.jivesoftware.smack.packet.Nonza;
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmppElementUtil;
 
-import org.jxmpp.util.XmppStringUtils;
-
 /**
  * Manages providers for parsing custom XML sub-documents of XMPP packets. Two types of
  * providers exist:<ul>
@@ -112,10 +112,10 @@ import org.jxmpp.util.XmppStringUtils;
  */
 public final class ProviderManager {
 
-    private static final Map<String, ExtensionElementProvider<ExtensionElement>> extensionProviders = new ConcurrentHashMap<String, ExtensionElementProvider<ExtensionElement>>();
-    private static final Map<String, IQProvider<IQ>> iqProviders = new ConcurrentHashMap<String, IQProvider<IQ>>();
-    private static final Map<String, ExtensionElementProvider<ExtensionElement>> streamFeatureProviders = new ConcurrentHashMap<String, ExtensionElementProvider<ExtensionElement>>();
-    private static final Map<String, NonzaProvider<? extends Nonza>> nonzaProviders = new ConcurrentHashMap<>();
+    private static final Map<QName, ExtensionElementProvider<ExtensionElement>> extensionProviders = new ConcurrentHashMap<>();
+    private static final Map<QName, IQProvider<IQ>> iqProviders = new ConcurrentHashMap<>();
+    private static final Map<QName, ExtensionElementProvider<ExtensionElement>> streamFeatureProviders = new ConcurrentHashMap<>();
+    private static final Map<QName, NonzaProvider<? extends Nonza>> nonzaProviders = new ConcurrentHashMap<>();
 
     static {
         // Ensure that Smack is initialized by calling getVersion, so that user
@@ -168,7 +168,7 @@ public final class ProviderManager {
      * @return the IQ provider.
      */
     public static IQProvider<IQ> getIQProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         return iqProviders.get(key);
     }
 
@@ -199,7 +199,7 @@ public final class ProviderManager {
             Object provider) {
         validate(elementName, namespace);
         // First remove existing providers
-        String key = removeIQProvider(elementName, namespace);
+        QName key = removeIQProvider(elementName, namespace);
         if (provider instanceof IQProvider) {
             iqProviders.put(key, (IQProvider<IQ>) provider);
         } else {
@@ -214,10 +214,10 @@ public final class ProviderManager {
      *
      * @param elementName the XML element name.
      * @param namespace the XML namespace.
-     * @return the key of the removed IQ Provider
+     * @return the QName of the removed provider
      */
-    public static String removeIQProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+    public static QName removeIQProvider(String elementName, String namespace) {
+        QName key = getQName(elementName, namespace);
         iqProviders.remove(key);
         return key;
     }
@@ -242,7 +242,7 @@ public final class ProviderManager {
      * @return the extension provider.
      */
     public static ExtensionElementProvider<ExtensionElement> getExtensionProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         return extensionProviders.get(key);
     }
 
@@ -260,7 +260,7 @@ public final class ProviderManager {
             Object provider) {
         validate(elementName, namespace);
         // First remove existing providers
-        String key = removeExtensionProvider(elementName, namespace);
+        QName key = removeExtensionProvider(elementName, namespace);
         if (provider instanceof ExtensionElementProvider) {
             extensionProviders.put(key, (ExtensionElementProvider<ExtensionElement>) provider);
         } else {
@@ -275,10 +275,10 @@ public final class ProviderManager {
      *
      * @param elementName the XML element name.
      * @param namespace the XML namespace.
-     * @return the key of the removed stanza extension provider
+     * @return the QName of the removed stanza extension provider
      */
-    public static String removeExtensionProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+    public static QName removeExtensionProvider(String elementName, String namespace) {
+        QName key = getQName(elementName, namespace);
         extensionProviders.remove(key);
         return key;
     }
@@ -297,48 +297,48 @@ public final class ProviderManager {
     }
 
     public static ExtensionElementProvider<ExtensionElement> getStreamFeatureProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         return streamFeatureProviders.get(key);
     }
 
     public static void addStreamFeatureProvider(String elementName, String namespace, ExtensionElementProvider<ExtensionElement> provider) {
         validate(elementName, namespace);
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         streamFeatureProviders.put(key, provider);
     }
 
     public static void removeStreamFeatureProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         streamFeatureProviders.remove(key);
     }
 
     public static NonzaProvider<? extends Nonza> getNonzaProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         return getNonzaProvider(key);
     }
 
-    public static NonzaProvider<? extends Nonza> getNonzaProvider(String key) {
+    public static NonzaProvider<? extends Nonza> getNonzaProvider(QName key) {
         return nonzaProviders.get(key);
     }
 
     public static void addNonzaProvider(NonzaProvider<? extends Nonza> nonzaProvider) {
         Class<? extends Nonza> nonzaClass = nonzaProvider.getElementClass();
-        String key = XmppElementUtil.getKeyFor(nonzaClass);
+        QName key = XmppElementUtil.getQNameFor(nonzaClass);
         nonzaProviders.put(key, nonzaProvider);
     }
 
     public static void removeNonzaProvider(Class<? extends Nonza> nonzaClass) {
-        String key = XmppElementUtil.getKeyFor(nonzaClass);
+        QName key = XmppElementUtil.getQNameFor(nonzaClass);
         nonzaProviders.remove(key);
     }
 
     public static void removeNonzaProvider(String elementName, String namespace) {
-        String key = getKey(elementName, namespace);
+        QName key = getQName(elementName, namespace);
         nonzaProviders.remove(key);
     }
 
-    private static String getKey(String elementName, String namespace) {
-        return XmppStringUtils.generateKey(elementName, namespace);
+    private static QName getQName(String elementName, String namespace) {
+        return new QName(namespace, elementName);
     }
 
     private static void validate(String elementName, String namespace) {

smack-core/src/main/java/org/jivesoftware/smack/provider/TlsFailureProvider.java

@@ -19,7 +19,7 @@ package org.jivesoftware.smack.provider;
 import org.jivesoftware.smack.packet.TlsProceed;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 
-import org.xmlpull.v1.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 public final class TlsFailureProvider extends NonzaProvider<TlsProceed> {
 

smack-core/src/main/java/org/jivesoftware/smack/provider/TlsProceedProvider.java

@@ -19,7 +19,7 @@ package org.jivesoftware.smack.provider;
 import org.jivesoftware.smack.packet.TlsFailure;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 
-import org.xmlpull.v1.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 public final class TlsProceedProvider extends NonzaProvider<TlsFailure> {
 

smack-core/src/main/java/org/jivesoftware/smack/proxy/Socks4ProxySocketConnection.java

@@ -22,8 +22,7 @@ import java.io.OutputStream;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
-
-import org.jivesoftware.smack.util.StringUtils;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Socket factory for socks4 proxy.
@@ -73,7 +72,6 @@ public class Socks4ProxySocketConnection implements ProxySocketConnection {
     of all zero bits.
     */
 
-            index = 0;
             buf[index++] = 4;
             buf[index++] = 1;
 
@@ -87,7 +85,7 @@ public class Socks4ProxySocketConnection implements ProxySocketConnection {
             }
 
             if (user != null) {
-                byte[] userBytes = user.getBytes(StringUtils.UTF8);
+                byte[] userBytes = user.getBytes(StandardCharsets.UTF_8);
                 System.arraycopy(userBytes, 0, buf, index, user.length());
                 index += user.length();
             }

smack-core/src/main/java/org/jivesoftware/smack/proxy/Socks5ProxySocketConnection.java

@@ -21,10 +21,10 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.nio.charset.StandardCharsets;
 import java.util.logging.Logger;
 
 import org.jivesoftware.smack.util.CloseableUtil;
-import org.jivesoftware.smack.util.StringUtils;
 
 /**
  * Socket factory for Socks5 proxy.
@@ -133,11 +133,11 @@ public class Socks5ProxySocketConnection implements ProxySocketConnection {
                     index = 0;
                     buf[index++] = 1;
                     buf[index++] = (byte) user.length();
-                    byte[] userBytes = user.getBytes(StringUtils.UTF8);
+                    byte[] userBytes = user.getBytes(StandardCharsets.UTF_8);
                     System.arraycopy(userBytes, 0, buf, index,
                         user.length());
                     index += user.length();
-                    byte[] passwordBytes = passwd.getBytes(StringUtils.UTF8);
+                    byte[] passwordBytes = passwd.getBytes(StandardCharsets.UTF_8);
                     buf[index++] = (byte) passwordBytes.length;
                     System.arraycopy(passwordBytes, 0, buf, index,
                         passwd.length());
@@ -204,7 +204,7 @@ public class Socks5ProxySocketConnection implements ProxySocketConnection {
             buf[index++] = 1;       // CONNECT
             buf[index++] = 0;
 
-            byte[] hostb = host.getBytes(StringUtils.UTF8);
+            byte[] hostb = host.getBytes(StandardCharsets.UTF_8);
             int len = hostb.length;
             buf[index++] = 3;      // DOMAINNAME
             buf[index++] = (byte) len;

smack-core/src/main/java/org/jivesoftware/smack/sasl/SASLErrorException.java

@@ -31,13 +31,13 @@ public class SASLErrorException extends XMPPException {
 
     private final SASLFailure saslFailure;
     private final String mechanism;
-    private final Map<String,String> texts;
+    private final Map<String, String> texts;
 
     public SASLErrorException(String mechanism, SASLFailure saslFailure) {
         this(mechanism, saslFailure, new HashMap<String, String>());
     }
 
-    public SASLErrorException(String mechanism, SASLFailure saslFailure, Map<String,String> texts) {
+    public SASLErrorException(String mechanism, SASLFailure saslFailure, Map<String, String> texts) {
         super("SASLError using " + mechanism + ": " + saslFailure.getSASLErrorString());
         this.mechanism = mechanism;
         this.saslFailure = saslFailure;
@@ -52,7 +52,7 @@ public class SASLErrorException extends XMPPException {
         return mechanism;
     }
 
-    public Map<String,String> getTexts() {
+    public Map<String, String> getTexts() {
         return texts;
     }
 }

smack-core/src/main/java/org/jivesoftware/smack/sasl/core/ScramMechanism.java

@@ -16,7 +16,7 @@
  */
 package org.jivesoftware.smack.sasl.core;
 
-import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 import java.security.InvalidKeyException;
 import java.security.SecureRandom;
 import java.util.Collections;
@@ -114,14 +114,8 @@ public abstract class ScramMechanism extends SASLMechanism {
 
     @Override
     protected byte[] evaluateChallenge(byte[] challenge) throws SmackSaslException {
-        String challengeString;
-        try {
-            // TODO: Where is it specified that this is an UTF-8 encoded string?
-            challengeString = new String(challenge, StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        // TODO: Where is it specified that this is an UTF-8 encoded string?
+        String challengeString = new String(challenge, StandardCharsets.UTF_8);
 
         switch (state) {
         case AUTH_TEXT_SENT:
@@ -386,14 +380,9 @@ public abstract class ScramMechanism extends SASLMechanism {
      * @throws SmackSaslException if a SASL related error occurs.
      */
     private byte[] hi(String normalizedPassword, byte[] salt, int iterations) throws SmackSaslException {
-        byte[] key;
-        try {
-            // According to RFC 5802 § 2.2, the resulting string of the normalization is also in UTF-8.
-            key = normalizedPassword.getBytes(StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new AssertionError();
-        }
+        // According to RFC 5802 § 2.2, the resulting string of the normalization is also in UTF-8.
+        byte[] key = normalizedPassword.getBytes(StandardCharsets.UTF_8);
+
         // U1 := HMAC(str, salt + INT(1))
         byte[] u = hmac(key, ByteUtils.concat(salt, ONE));
         byte[] res = u.clone();

smack-core/src/main/java/org/jivesoftware/smack/util/ArrayBlockingQueueWithShutdown.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2014-2018 Florian Schmaus
+ * Copyright 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -110,7 +110,7 @@ public class ArrayBlockingQueueWithShutdown<E> extends AbstractQueue<E> implemen
 
     private void checkNotShutdown() throws InterruptedException {
         if (isShutdown) {
-            throw new InterruptedException();
+            throw new InterruptedException("Queue was already shut down");
         }
     }
 

smack-core/src/main/java/org/jivesoftware/smack/util/CallbackRecipient.java

@@ -16,7 +16,7 @@
  */
 package org.jivesoftware.smack.util;
 
-public interface CallbackRecipient<V,E> {
+public interface CallbackRecipient<V, E> {
 
     CallbackRecipient<V, E> onSuccess(SuccessCallback<V> successCallback);
 

smack-core/src/main/java/org/jivesoftware/smack/util/CloseableUtil.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2018 Florian Schmaus
+ * Copyright 2018-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,10 @@ import java.util.logging.Logger;
 
 public class CloseableUtil {
 
+    public static void maybeClose(Closeable closable) {
+        maybeClose(closable, null);
+    }
+
     public static void maybeClose(Closeable closable, Logger logger) {
         if (closable == null) {
             return;
@@ -31,7 +35,9 @@ public class CloseableUtil {
         try {
             closable.close();
         } catch (IOException e) {
-            logger.log(Level.WARNING, "Could not close " + closable, e);
+            if (logger != null) {
+                logger.log(Level.WARNING, "Could not close " + closable, e);
+            }
         }
     }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/CollectionUtil.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2015-2018 Florian Schmaus
+ * Copyright 2015-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,4 +49,10 @@ public class CollectionUtil {
     public interface Predicate<T> {
         boolean test(T t);
     }
+
+    public static <T> ArrayList<T> newListWith(Collection<? extends T> collection) {
+        ArrayList<T> arrayList = new ArrayList<>(collection.size());
+        arrayList.addAll(collection);
+        return arrayList;
+    }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/EqualsUtil.java

@@ -0,0 +1,243 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+public final class EqualsUtil {
+
+    private EqualsUtil() {
+    }
+
+    public static <T> boolean equals(T thisObject, Object other, EqualsComperator<T> equalsComperator) {
+        if (other == null) {
+            return false;
+        }
+        if (thisObject == other) {
+            return true;
+        }
+        @SuppressWarnings("unchecked")
+        Class<T> thisObjectClass = (Class<T>) thisObject.getClass();
+        if (thisObjectClass != other.getClass()) {
+            return false;
+        }
+
+        EqualsUtil.Builder equalsBuilder = new EqualsUtil.Builder();
+
+        equalsComperator.compare(equalsBuilder, thisObjectClass.cast(other));
+
+        return equalsBuilder.isEquals;
+    }
+
+    @FunctionalInterface
+    public interface EqualsComperator<T> {
+        void compare(EqualsUtil.Builder equalsBuilder, T other);
+    }
+
+    public static final class Builder {
+        private boolean isEquals = true;
+
+        private Builder() {
+        }
+
+        private void nullSafeCompare(Object left, Object right, Runnable runnable) {
+            if (!isEquals) {
+                return;
+            }
+
+            if (left == right) {
+                return;
+            }
+
+            if (left == null || right == null) {
+                isEquals = false;
+                return;
+            }
+
+            runnable.run();
+        }
+
+        public <O> Builder append(O left, O right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            if (left == right) {
+                return this;
+            }
+
+            if (left == null || right == null) {
+                isEquals = false;
+                return this;
+            }
+
+            isEquals = left.equals(right);
+            return this;
+        }
+
+        public Builder append(boolean left, boolean right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            isEquals = left == right;
+            return this;
+        }
+
+        public Builder append(boolean[] left, boolean[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+
+        public Builder append(byte left, byte right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            isEquals = left == right;
+            return this;
+        }
+
+        public Builder append(byte[] left, byte[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+
+        public Builder append(char left, char right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            isEquals = left == right;
+            return this;
+        }
+
+        public Builder append(char[] left, char[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+
+        public Builder append(double left, double right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            return append(Double.doubleToLongBits(left), Double.doubleToLongBits(right));
+        }
+
+        public Builder append(double[] left, double[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+
+        public Builder append(float left, float right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            return append(Float.floatToIntBits(left), Float.floatToIntBits(right));
+        }
+
+        public Builder append(float[] left, float[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+
+        public Builder append(int left, int right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            isEquals = left == right;
+            return this;
+        }
+
+        public Builder append(int[] left, int[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+
+        public Builder append(long left, long right) {
+            if (!isEquals) {
+                return this;
+            }
+
+            isEquals = left == right;
+            return this;
+        }
+
+        public Builder append(long[] left, long[] right) {
+            nullSafeCompare(left, right, () -> {
+                if (left.length != right.length) {
+                    isEquals = false;
+                    return;
+                }
+                for (int i = 0; i < left.length && isEquals; i++) {
+                    append(left[i], right[i]);
+                }
+            });
+            return this;
+        }
+    }
+
+}

smack-core/src/main/java/org/jivesoftware/smack/util/EventManger.java

@@ -34,7 +34,7 @@ import java.util.concurrent.ConcurrentHashMap;
  */
 public class EventManger<K, R, E extends Exception> {
 
-    private final Map<K,Reference<R>> events = new ConcurrentHashMap<>();
+    private final Map<K, Reference<R>> events = new ConcurrentHashMap<>();
 
     /**
      * Perform an action and wait for an event.

smack-core/src/main/java/org/jivesoftware/smack/util/FileUtils.java

@@ -30,6 +30,7 @@ import java.io.Reader;
 import java.net.MalformedURLException;
 import java.net.URI;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
@@ -90,7 +91,7 @@ public final class FileUtils {
     public static boolean addLines(String uriString, Set<String> set) throws MalformedURLException, IOException {
         URI uri = URI.create(uriString);
         InputStream is = getStreamForUri(uri, null);
-        InputStreamReader sr = new InputStreamReader(is, StringUtils.UTF8);
+        InputStreamReader sr = new InputStreamReader(is, StandardCharsets.UTF_8);
         BufferedReader br = new BufferedReader(sr);
         try {
             String line;

smack-core/src/main/java/org/jivesoftware/smack/util/HashCode.java

@@ -0,0 +1,211 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+public class HashCode {
+
+    private static final int MULTIPLIER_VALUE = 37;
+
+    public static class Cache {
+        private boolean calculated;
+        private int hashcode;
+
+        public int getHashCode(Calculator hashCodeCalculator) {
+            if (calculated) {
+                return hashcode;
+            }
+
+            HashCode.Builder hashCodeBuilder = new HashCode.Builder();
+            hashCodeCalculator.calculateHash(hashCodeBuilder);
+
+            calculated = true;
+            hashcode = hashCodeBuilder.hashcode;
+
+            return hashcode;
+        }
+
+    }
+
+    @FunctionalInterface
+    public interface Calculator {
+        void calculateHash(HashCode.Builder hashCodeBuilder);
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+        private int hashcode = 17;
+
+        private void applyHash() {
+            applyHash(0);
+        }
+
+        private void applyHash(int hash) {
+            hashcode = MULTIPLIER_VALUE * hashcode + hash;
+        }
+
+        public Builder append(Object object) {
+            if (object == null) {
+                applyHash();
+                return this;
+            }
+
+            if (object.getClass().isArray()) {
+                if (object instanceof int[]) {
+                    append((int[]) object);
+                } else if (object instanceof long[]) {
+                    append((long[]) object);
+                } else if (object instanceof boolean[]) {
+                    append((boolean[]) object);
+                } else if (object instanceof double[]) {
+                    append((double[]) object);
+                } else if (object instanceof float[]) {
+                    append((float[]) object);
+                } else if (object instanceof short[]) {
+                    append((short[]) object);
+                } else if (object instanceof char[]) {
+                    append((char[]) object);
+                } else if (object instanceof byte[]) {
+                    append((byte[]) object);
+                } else {
+                    append((Object[]) object);
+                }
+            }
+            applyHash(object.hashCode());
+            return this;
+        }
+
+        public Builder append(boolean value) {
+            applyHash(value ? 0 : 1);
+            return this;
+        }
+
+        public Builder append(boolean[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (boolean bool : array) {
+                append(bool);
+            }
+            return this;
+        }
+
+        public Builder append(byte value) {
+            applyHash(value);
+            return this;
+        }
+
+        public Builder append(byte[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (byte b : array) {
+                append(b);
+            }
+            return this;
+        }
+
+        public Builder append(char value) {
+            applyHash(value);
+            return this;
+        }
+
+        public Builder append(char[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (char c : array) {
+                append(c);
+            }
+            return this;
+        }
+
+        public Builder append(double value) {
+            return append(Double.doubleToLongBits(value));
+        }
+
+        public Builder append(double[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (double d : array) {
+                append(d);
+            }
+            return this;
+        }
+
+        public Builder append(float value) {
+            return append(Float.floatToIntBits(value));
+        }
+
+        public Builder append(float[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (float f : array) {
+                append(f);
+            }
+            return this;
+        }
+
+        public Builder append(long value) {
+            applyHash((int) (value ^ (value >>> 32)));
+            return this;
+        }
+
+        public Builder append(long[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (long l : array) {
+                append(l);
+            }
+            return this;
+        }
+
+        public Builder append(Object[] array) {
+            if (array == null) {
+                applyHash();
+                return this;
+            }
+
+            for (Object element : array) {
+                append(element);
+            }
+            return this;
+        }
+
+        public int build() {
+            return hashcode;
+        }
+    }
+
+}

smack-core/src/main/java/org/jivesoftware/smack/util/InternetAddress.java

@@ -0,0 +1,213 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+import org.minidns.dnslabel.DnsLabel;
+import org.minidns.dnsname.DnsName;
+import org.minidns.dnsname.InvalidDnsNameException;
+import org.minidns.util.InetAddressUtil;
+
+/**
+ * An internet address, can be given as IP or as DNS name.
+ * <p>
+ * This type is meant for strings that hold an internet address. The original string used to construct this type is
+ * stored and returning in the {@link #toString()} method.
+ * </p>
+ *
+ * @since 4.4.0
+ */
+public abstract class InternetAddress implements CharSequence {
+
+    protected final String originalString;
+
+    protected InternetAddress(String originalString) {
+        this.originalString = Objects.requireNonNull(originalString, "The 'originalString' argument must not be null");
+    }
+
+    public abstract InetAddress asInetAddress() throws UnknownHostException;
+
+    @Override
+    public String toString() {
+        return originalString;
+    }
+
+    @Override
+    public int length() {
+        return originalString.length();
+    }
+
+    @Override
+    public char charAt(int index) {
+        return originalString.charAt(index);
+    }
+
+    @Override
+    public CharSequence subSequence(int start, int end) {
+        return originalString.subSequence(start, end);
+    }
+
+    public static InternetAddress from(String address) {
+        final InternetAddress internetAddress;
+        if (InetAddressUtil.isIpV4Address(address)) {
+            internetAddress = new InternetAddress.Ipv4(address);
+        } else if (InetAddressUtil.isIpV6Address(address)) {
+            internetAddress = new InternetAddress.Ipv6(address);
+        } else if (address.contains(".")) {
+            InternetAddress domainNameInternetAddress;
+            try {
+                DnsName dnsName = DnsName.from(address);
+                domainNameInternetAddress = new InternetAddress.DomainName(address, dnsName);
+            } catch (InvalidDnsNameException e) {
+                domainNameInternetAddress = new InternetAddress.InvalidDomainName(address, e);
+            }
+            internetAddress = domainNameInternetAddress;
+        } else {
+            DnsLabel dnsLabel = DnsLabel.from(address);
+            internetAddress = new InternetAddress.DomainNameLabel(address, dnsLabel);
+        }
+        return internetAddress;
+    }
+
+    public static InternetAddress from(InetAddress inetAddress) {
+        if (inetAddress instanceof Inet4Address) {
+            return new InternetAddress.Ipv4(inetAddress.getHostAddress(), (Inet4Address) inetAddress);
+        } else if (inetAddress instanceof Inet6Address) {
+            return new InternetAddress.Ipv6(inetAddress.getHostAddress(), (Inet6Address) inetAddress);
+        } else {
+            throw new IllegalArgumentException("Unknown type " + inetAddress.getClass() + " of " + inetAddress);
+        }
+    }
+
+    private static class InetAddressInternetAddress extends InternetAddress {
+        private final InetAddress inetAddress;
+
+        protected InetAddressInternetAddress(String originalString, InetAddress inetAddress) {
+            super(originalString);
+            this.inetAddress = inetAddress;
+        }
+
+        @Override
+        public InetAddress asInetAddress() {
+            return inetAddress;
+        }
+    }
+
+    public static final class Ipv4 extends InetAddressInternetAddress {
+
+        private final Inet4Address inet4Address;
+
+        private Ipv4(String originalString) {
+            this(originalString, InetAddressUtil.ipv4From(originalString));
+        }
+
+        private Ipv4(String originalString, Inet4Address inet4Address) {
+            super(originalString, inet4Address);
+            this.inet4Address = inet4Address;
+        }
+
+        public Inet4Address getInet4Address() {
+            return inet4Address;
+        }
+    }
+
+    public static final class Ipv6 extends InetAddressInternetAddress {
+
+        private Inet6Address inet6Address;
+
+        private Ipv6(String originalString) {
+            this(originalString, InetAddressUtil.ipv6From(originalString));
+        }
+
+        private Ipv6(String originalString, Inet6Address inet6Address) {
+            super(originalString, inet6Address);
+            this.inet6Address = inet6Address;
+        }
+
+        public Inet6Address getInet6Address() {
+            return inet6Address;
+        }
+    }
+
+    private static class NonNumericInternetAddress extends InternetAddress {
+        private boolean attemptedToResolveInetAddress;
+        private InetAddress inetAddress;
+
+        protected NonNumericInternetAddress(String originalString) {
+            super(originalString);
+        }
+
+        @Override
+        public InetAddress asInetAddress() throws UnknownHostException {
+            if (inetAddress != null || attemptedToResolveInetAddress) {
+                return inetAddress;
+            }
+
+            attemptedToResolveInetAddress = true;
+            inetAddress = InetAddress.getByName(originalString);
+
+            return inetAddress;
+        }
+    }
+
+    public static final class DomainName extends NonNumericInternetAddress {
+
+        private final DnsName dnsName;
+
+        private DomainName(String originalString, DnsName dnsName) {
+            super(originalString);
+            this.dnsName = dnsName;
+        }
+
+        public DnsName getDnsName() {
+            return dnsName;
+        }
+
+    }
+
+    public static final class DomainNameLabel extends NonNumericInternetAddress {
+
+        private final DnsLabel dnsLabel;
+
+        private DomainNameLabel(String originalString, DnsLabel dnsLabel) {
+            super(originalString);
+            this.dnsLabel = dnsLabel;
+        }
+
+        public DnsLabel getDnsLabel() {
+            return dnsLabel;
+        }
+    }
+
+    public static final class InvalidDomainName extends NonNumericInternetAddress {
+
+        private final InvalidDnsNameException invalidDnsNameException;
+
+        private InvalidDomainName(String originalString, InvalidDnsNameException invalidDnsNameException) {
+            super(originalString);
+            this.invalidDnsNameException = invalidDnsNameException;
+        }
+
+        public InvalidDnsNameException getInvalidDnsNameException() {
+            return invalidDnsNameException;
+        }
+    }
+}

smack-core/src/main/java/org/jivesoftware/smack/util/MultiMap.java

@@ -22,6 +22,7 @@ import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Set;
 
 /**
@@ -33,7 +34,7 @@ import java.util.Set;
  * @param <K> the type of the keys the map uses.
  * @param <V> the type of the values the map uses.
  */
-public class MultiMap<K,V> {
+public class MultiMap<K, V> {
 
     /**
      * The constant value {@value}.
@@ -57,7 +58,11 @@ public class MultiMap<K,V> {
      * @param size the initial capacity.
      */
     public MultiMap(int size) {
-        map = new LinkedHashMap<>(size);
+        this(new LinkedHashMap<>(size));
+    }
+
+    private MultiMap(Map<K, List<V>> map) {
+        this.map = map;
     }
 
     public int size() {
@@ -72,11 +77,11 @@ public class MultiMap<K,V> {
         return map.isEmpty();
     }
 
-    public boolean containsKey(Object key) {
+    public boolean containsKey(K key) {
         return map.containsKey(key);
     }
 
-    public boolean containsValue(Object value) {
+    public boolean containsValue(V value) {
         for (List<V> list : map.values()) {
             if (list.contains(value)) {
                 return true;
@@ -91,7 +96,7 @@ public class MultiMap<K,V> {
      * @param key
      * @return the first value or null.
      */
-    public V getFirst(Object key) {
+    public V getFirst(K key) {
         List<V> res = getAll(key);
         if (res.isEmpty()) {
             return null;
@@ -109,7 +114,7 @@ public class MultiMap<K,V> {
      * @param key
      * @return all values for the given key.
      */
-    public List<V> getAll(Object key) {
+    public List<V> getAll(K key) {
         List<V> res = map.get(key);
         if (res == null) {
             res = Collections.emptyList();
@@ -138,7 +143,7 @@ public class MultiMap<K,V> {
      * @param key
      * @return the first value of the given key or null.
      */
-    public V remove(Object key) {
+    public V remove(K key) {
         List<V> res = map.remove(key);
         if (res == null) {
             return null;
@@ -157,7 +162,7 @@ public class MultiMap<K,V> {
      * @param value
      * @return true if the mapping was removed, false otherwise.
      */
-    public boolean removeOne(Object key, V value) {
+    public boolean removeOne(K key, V value) {
         List<V> list = map.get(key);
         if (list == null) {
             return false;
@@ -235,6 +240,18 @@ public class MultiMap<K,V> {
         return entrySet;
     }
 
+    public MultiMap<K, V> asUnmodifiableMultiMap() {
+        LinkedHashMap<K, List<V>> mapCopy = new LinkedHashMap<>(map.size());
+        for (Entry<K, List<V>> entry : map.entrySet()) {
+            K key = entry.getKey();
+            List<V> values = entry.getValue();
+
+            mapCopy.put(key, Collections.unmodifiableList(values));
+        }
+
+        return new MultiMap<K, V>(Collections.unmodifiableMap(mapCopy));
+    }
+
     private static final class SimpleMapEntry<K, V> implements Map.Entry<K, V> {
 
         private final K key;

smack-core/src/main/java/org/jivesoftware/smack/util/NumberUtil.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2015 Florian Schmaus
+ * Copyright © 2015-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,13 +22,41 @@ public class NumberUtil {
      * Checks if the given long is within the range of an unsigned 32-bit integer, the XML type "xs:unsignedInt".
      *
      * @param value
+     * @deprecated use {@link #requireUInt32(long)} instead.
      */
+    @Deprecated
+    // TODO: Remove in Smack 4.5.
     public static void checkIfInUInt32Range(long value) {
+        requireUInt32(value);
+    }
+
+    /**
+     * Checks if the given long is within the range of an unsigned 32-bit integer, the XML type "xs:unsignedInt".
+     *
+     * @param value
+     */
+    public static long requireUInt32(long value) {
         if (value < 0) {
             throw new IllegalArgumentException("unsigned 32-bit integers can't be negative");
         }
         if (value > ((1L << 32) - 1)) {
             throw new IllegalArgumentException("unsigned 32-bit integers can't be greater then 2^32 - 1");
         }
+        return value;
+    }
+
+    /**
+     * Checks if the given int is within the range of an unsigned 16-bit integer, the XML type "xs:unsignedShort".
+     *
+     * @param value
+     */
+    public static int requireUShort16(int value) {
+        if (value < 0) {
+            throw new IllegalArgumentException("unsigned 16-bit integers can't be negative");
+        }
+        if (value > ((1 << 16) - 1)) {
+            throw new IllegalArgumentException("unsigned 16-bit integers can't be greater than 2^16 - 1");
+        }
+        return value;
     }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/Objects.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2015-2018 Florian Schmaus
+ * Copyright 2015-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,9 +20,26 @@ import java.util.Collection;
 
 public class Objects {
 
-    public static <T> T requireNonNull(T obj, String message) {
+    /**
+     * Checks that the specified object reference is not <code>null</code> and throws a customized
+     * {@link IllegalArgumentException} if it is.
+     * <p>
+     * Note that unlike <code>java.util.Objects</code>, this method throws an {@link IllegalArgumentException} instead
+     * of an {@link NullPointerException}.
+     * </p>
+     *
+     * @param <T> the type of the reference.
+     * @param obj the object reference to check for nullity.
+     * @param message detail message to be used in the event that a {@link IllegalArgumentException} is thrown.
+     * @return <code>obj</code> if not null.
+     * @throws IllegalArgumentException in case <code>obj</code> is <code>null</code>.
+     */
+    public static <T> T requireNonNull(T obj, String message) throws IllegalArgumentException {
         if (obj == null) {
-            throw new NullPointerException(message);
+            if (message == null) {
+                message = "Can not provide null argument";
+            }
+            throw new IllegalArgumentException(message);
         }
         return obj;
     }

smack-core/src/main/java/org/jivesoftware/smack/util/PacketParserUtils.java

@@ -17,18 +17,19 @@
 package org.jivesoftware.smack.util;
 
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.io.Reader;
 import java.io.StringReader;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.logging.Level;
 import java.util.logging.Logger;
 
-import org.jivesoftware.smack.SmackConfiguration;
 import org.jivesoftware.smack.compress.packet.Compress;
 import org.jivesoftware.smack.packet.EmptyResultIQ;
 import org.jivesoftware.smack.packet.ErrorIQ;
@@ -49,11 +50,12 @@ import org.jivesoftware.smack.provider.ExtensionElementProvider;
 import org.jivesoftware.smack.provider.IQProvider;
 import org.jivesoftware.smack.provider.ProviderManager;
 import org.jivesoftware.smack.sasl.packet.SaslStreamElements.SASLFailure;
+import org.jivesoftware.smack.xml.SmackXmlParser;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jxmpp.jid.Jid;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
-import org.xmlpull.v1.XmlPullParserFactory;
+import org.jxmpp.stringprep.XmppStringprepException;
 
 /**
  * Utility class that helps to parse packets. Any parsing packets method that must be shared
@@ -64,51 +66,22 @@ import org.xmlpull.v1.XmlPullParserFactory;
 public class PacketParserUtils {
     private static final Logger LOGGER = Logger.getLogger(PacketParserUtils.class.getName());
 
-    public static final String FEATURE_XML_ROUNDTRIP = "http://xmlpull.org/v1/doc/features.html#xml-roundtrip";
-
-    private static final XmlPullParserFactory XML_PULL_PARSER_FACTORY;
-
-    /**
-     * True if the XmlPullParser supports the XML_ROUNDTRIP feature.
-     */
-    public static final boolean XML_PULL_PARSER_SUPPORTS_ROUNDTRIP;
-
-    static {
-        // Ensure that Smack is initialized.
-        SmackConfiguration.getVersion();
-
-        XmlPullParser xmlPullParser;
-        boolean roundtrip = false;
-        try {
-            XML_PULL_PARSER_FACTORY = XmlPullParserFactory.newInstance();
-            xmlPullParser = XML_PULL_PARSER_FACTORY.newPullParser();
-            try {
-                xmlPullParser.setFeature(FEATURE_XML_ROUNDTRIP, true);
-                // We could successfully set the feature
-                roundtrip = true;
-            } catch (XmlPullParserException e) {
-                // Doesn't matter if FEATURE_XML_ROUNDTRIP isn't available
-                LOGGER.log(Level.FINEST, "XmlPullParser does not support XML_ROUNDTRIP", e);
-            }
-        }
-        catch (XmlPullParserException e) {
-            // Something really bad happened
-            throw new AssertionError(e);
-        }
-        XML_PULL_PARSER_SUPPORTS_ROUNDTRIP = roundtrip;
-    }
-
     // TODO: Rename argument name from 'stanza' to 'element'.
     public static XmlPullParser getParserFor(String stanza) throws XmlPullParserException, IOException {
         return getParserFor(new StringReader(stanza));
     }
 
+    public static XmlPullParser getParserFor(InputStream inputStream) throws XmlPullParserException {
+        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
+        return SmackXmlParser.newXmlParser(inputStreamReader);
+    }
+
     public static XmlPullParser getParserFor(Reader reader) throws XmlPullParserException, IOException {
-        XmlPullParser parser = newXmppParser(reader);
+        XmlPullParser parser = SmackXmlParser.newXmlParser(reader);
         // Wind the parser forward to the first start tag
-        int event = parser.getEventType();
-        while (event != XmlPullParser.START_TAG) {
-            if (event == XmlPullParser.END_DOCUMENT) {
+        XmlPullParser.Event event = parser.getEventType();
+        while (event != XmlPullParser.Event.START_ELEMENT) {
+            if (event == XmlPullParser.Event.END_DOCUMENT) {
                 throw new IllegalArgumentException("Document contains no start tag");
             }
             event = parser.next();
@@ -116,28 +89,8 @@ public class PacketParserUtils {
         return parser;
     }
 
-    public static XmlPullParser getParserFor(String stanza, String startTag)
-                    throws XmlPullParserException, IOException {
-        XmlPullParser parser = getParserFor(stanza);
-
-        while (true) {
-            int event = parser.getEventType();
-            String name = parser.getName();
-            if (event == XmlPullParser.START_TAG && name.equals(startTag)) {
-                break;
-            }
-            else if (event == XmlPullParser.END_DOCUMENT) {
-                throw new IllegalArgumentException("Could not find start tag '" + startTag
-                                + "' in stanza: " + stanza);
-            }
-            parser.next();
-        }
-
-        return parser;
-    }
-
     @SuppressWarnings("unchecked")
-    public static <S extends Stanza> S parseStanza(String stanza) throws Exception {
+    public static <S extends Stanza> S parseStanza(String stanza) throws XmlPullParserException, SmackParsingException, IOException {
         return (S) parseStanza(getParserFor(stanza), null);
     }
 
@@ -149,9 +102,11 @@ public class PacketParserUtils {
      * @param parser
      * @param outerXmlEnvironment the outer XML environment (optional).
      * @return a stanza which is either a Message, IQ or Presence.
-     * @throws Exception
+     * @throws XmlPullParserException
+     * @throws SmackParsingException
+     * @throws IOException
      */
-    public static Stanza parseStanza(XmlPullParser parser, XmlEnvironment outerXmlEnvironment) throws Exception {
+    public static Stanza parseStanza(XmlPullParser parser, XmlEnvironment outerXmlEnvironment) throws XmlPullParserException, SmackParsingException, IOException {
         ParserUtils.assertAtStartTag(parser);
         final String name = parser.getName();
         switch (name) {
@@ -166,53 +121,6 @@ public class PacketParserUtils {
         }
     }
 
-    /**
-     * Creates a new XmlPullParser suitable for parsing XMPP. This means in particular that
-     * FEATURE_PROCESS_NAMESPACES is enabled.
-     * <p>
-     * Note that not all XmlPullParser implementations will return a String on
-     * <code>getText()</code> if the parser is on START_TAG or END_TAG. So you must not rely on this
-     * behavior when using the parser.
-     * </p>
-     *
-     * @return A suitable XmlPullParser for XMPP parsing
-     * @throws XmlPullParserException
-     */
-    public static XmlPullParser newXmppParser() throws XmlPullParserException {
-        XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
-        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
-        if (XML_PULL_PARSER_SUPPORTS_ROUNDTRIP) {
-            try {
-                parser.setFeature(FEATURE_XML_ROUNDTRIP, true);
-            }
-            catch (XmlPullParserException e) {
-                LOGGER.log(Level.SEVERE,
-                                "XmlPullParser does not support XML_ROUNDTRIP, although it was first determined to be supported",
-                                e);
-            }
-        }
-        return parser;
-    }
-
-    /**
-     * Creates a new XmlPullParser suitable for parsing XMPP. This means in particular that
-     * FEATURE_PROCESS_NAMESPACES is enabled.
-     * <p>
-     * Note that not all XmlPullParser implementations will return a String on
-     * <code>getText()</code> if the parser is on START_TAG or END_TAG. So you must not rely on this
-     * behavior when using the parser.
-     * </p>
-     *
-     * @param reader
-     * @return A suitable XmlPullParser for XMPP parsing
-     * @throws XmlPullParserException
-     */
-    public static XmlPullParser newXmppParser(Reader reader) throws XmlPullParserException {
-        XmlPullParser parser = newXmppParser();
-        parser.setInput(reader);
-        return parser;
-    }
-
     public static Message parseMessage(XmlPullParser parser) throws XmlPullParserException, IOException, SmackParsingException {
         return parseMessage(parser, null);
     }
@@ -249,9 +157,9 @@ public class PacketParserUtils {
         // in arbitrary sub-elements.
         String thread = null;
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String elementName = parser.getName();
                 String namespace = parser.getNamespace();
                 switch (elementName) {
@@ -276,11 +184,12 @@ public class PacketParserUtils {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default: // fall out
             }
         }
 
@@ -295,9 +204,9 @@ public class PacketParserUtils {
 
     /**
      * Returns the textual content of an element as String. After this method returns the parser
-     * position will be END_TAG, following the established pull parser calling convention.
+     * position will be END_ELEMENT, following the established pull parser calling convention.
      * <p>
-     * The parser must be positioned on a START_TAG of an element which MUST NOT contain Mixed
+     * The parser must be positioned on a START_ELEMENT of an element which MUST NOT contain Mixed
      * Content (as defined in XML 3.2.2), or else an XmlPullParserException will be thrown.
      * </p>
      * This method is used for the parts where the XMPP specification requires elements that contain
@@ -309,41 +218,36 @@ public class PacketParserUtils {
      * @throws IOException
      */
     public static String parseElementText(XmlPullParser parser) throws XmlPullParserException, IOException {
-        assert (parser.getEventType() == XmlPullParser.START_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.START_ELEMENT);
         String res;
-        if (parser.isEmptyElementTag()) {
-            res = "";
-        }
-        else {
-            // Advance to the text of the Element
-            int event = parser.next();
-            if (event != XmlPullParser.TEXT) {
-                if (event == XmlPullParser.END_TAG) {
-                    // Assume this is the end tag of the start tag at the
-                    // beginning of this method. Typical examples where this
-                    // happens are body elements containing the empty string,
-                    // ie. <body></body>, which appears to be valid XMPP, or a
-                    // least it's not explicitly forbidden by RFC 6121 5.2.3
-                    return "";
-                } else {
-                    throw new XmlPullParserException(
-                                    "Non-empty element tag not followed by text, while Mixed Content (XML 3.2.2) is disallowed");
-                }
-            }
-            res = parser.getText();
-            event = parser.next();
-            if (event != XmlPullParser.END_TAG) {
+        // Advance to the text of the Element
+        XmlPullParser.Event event = parser.next();
+        if (event != XmlPullParser.Event.TEXT_CHARACTERS) {
+            if (event == XmlPullParser.Event.END_ELEMENT) {
+                // Assume this is the end tag of the start tag at the
+                // beginning of this method. Typical examples where this
+                // happens are body elements containing the empty string,
+                // ie. <body></body>, which appears to be valid XMPP, or a
+                // least it's not explicitly forbidden by RFC 6121 5.2.3
+                return "";
+            } else {
                 throw new XmlPullParserException(
-                                "Non-empty element tag contains child-elements, while Mixed Content (XML 3.2.2) is disallowed");
+                                "Non-empty element tag not followed by text, while Mixed Content (XML 3.2.2) is disallowed");
             }
         }
+        res = parser.getText();
+        event = parser.next();
+        if (event != XmlPullParser.Event.END_ELEMENT) {
+            throw new XmlPullParserException(
+                            "Non-empty element tag contains child-elements, while Mixed Content (XML 3.2.2) is disallowed");
+        }
         return res;
     }
 
     /**
      * Returns the current element as string.
      * <p>
-     * The parser must be positioned on START_TAG.
+     * The parser must be positioned on START_ELEMENT.
      * </p>
      * Note that only the outermost namespace attributes ("xmlns") will be returned, not nested ones.
      *
@@ -359,37 +263,10 @@ public class PacketParserUtils {
     public static CharSequence parseElement(XmlPullParser parser,
                     boolean fullNamespaces) throws XmlPullParserException,
                     IOException {
-        assert (parser.getEventType() == XmlPullParser.START_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.START_ELEMENT);
         return parseContentDepth(parser, parser.getDepth(), fullNamespaces);
     }
 
-    /**
-     * Returns the content of a element.
-     * <p>
-     * The parser must be positioned on the START_TAG of the element which content is going to get
-     * returned. If the current element is the empty element, then the empty string is returned. If
-     * it is a element which contains just text, then just the text is returned. If it contains
-     * nested elements (and text), then everything from the current opening tag to the corresponding
-     * closing tag of the same depth is returned as String.
-     * </p>
-     * Note that only the outermost namespace attributes ("xmlns") will be returned, not nested ones.
-     *
-     * @param parser the XML pull parser
-     * @return the content of a tag
-     * @throws XmlPullParserException if parser encounters invalid XML
-     * @throws IOException if an IO error occurs
-     */
-    public static CharSequence parseContent(XmlPullParser parser)
-                    throws XmlPullParserException, IOException {
-        assert (parser.getEventType() == XmlPullParser.START_TAG);
-        if (parser.isEmptyElementTag()) {
-            return "";
-        }
-        // Advance the parser, since we want to parse the content of the current element
-        parser.next();
-        return parseContentDepth(parser, parser.getDepth(), false);
-    }
-
     public static CharSequence parseContentDepth(XmlPullParser parser, int depth)
                     throws XmlPullParserException, IOException {
         return parseContentDepth(parser, depth, false);
@@ -402,7 +279,7 @@ public class PacketParserUtils {
      * parent elements will be added to child elements that don't define a different namespace.
      * <p>
      * This method is able to parse the content with MX- and KXmlParser. KXmlParser does not support
-     * xml-roundtrip. i.e. return a String on getText() on START_TAG and END_TAG. We check for the
+     * xml-roundtrip. i.e. return a String on getText() on START_ELEMENT and END_ELEMENT. We check for the
      * XML_ROUNDTRIP feature. If it's not found we are required to work around this limitation, which
      * results in only partial support for XML namespaces ("xmlns"): Only the outermost namespace of
      * elements will be included in the resulting String, if <code>fullNamespaces</code> is set to false.
@@ -419,7 +296,7 @@ public class PacketParserUtils {
      * @throws IOException
      */
     public static CharSequence parseContentDepth(XmlPullParser parser, int depth, boolean fullNamespaces) throws XmlPullParserException, IOException {
-        if (parser.getFeature(FEATURE_XML_ROUNDTRIP)) {
+        if (parser.supportsRoundtrip()) {
             return parseContentDepthWithRoundtrip(parser, depth, fullNamespaces);
         } else {
             return parseContentDepthWithoutRoundtrip(parser, depth, fullNamespaces);
@@ -429,15 +306,21 @@ public class PacketParserUtils {
     private static CharSequence parseContentDepthWithoutRoundtrip(XmlPullParser parser, int depth,
                     boolean fullNamespaces) throws XmlPullParserException, IOException {
         XmlStringBuilder xml = new XmlStringBuilder();
-        int event = parser.getEventType();
-        boolean isEmptyElement = false;
+        XmlPullParser.Event event = parser.getEventType();
         // XmlPullParser reports namespaces in nested elements even if *only* the outer ones defines
         // it. This 'flag' ensures that when a namespace is set for an element, it won't be set again
         // in a nested element. It's an ugly workaround that has the potential to break things.
         String namespaceElement = null;
+        boolean startElementJustSeen = false;
         outerloop: while (true) {
             switch (event) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
+                if (startElementJustSeen) {
+                    xml.rightAngleBracket();
+                }
+                else {
+                    startElementJustSeen = true;
+                }
                 xml.halfOpenElement(parser.getName());
                 if (namespaceElement == null || fullNamespaces) {
                     String namespace = parser.getNamespace();
@@ -449,18 +332,11 @@ public class PacketParserUtils {
                 for (int i = 0; i < parser.getAttributeCount(); i++) {
                     xml.attribute(parser.getAttributeName(i), parser.getAttributeValue(i));
                 }
-                if (parser.isEmptyElementTag()) {
-                    xml.closeEmptyElement();
-                    isEmptyElement = true;
-                }
-                else {
-                    xml.rightAngleBracket();
-                }
                 break;
-            case XmlPullParser.END_TAG:
-                if (isEmptyElement) {
-                    // Do nothing as the element was already closed, just reset the flag
-                    isEmptyElement = false;
+            case END_ELEMENT:
+                if (startElementJustSeen) {
+                    xml.closeEmptyElement();
+                    startElementJustSeen = false;
                 }
                 else {
                     xml.closeElement(parser.getName());
@@ -474,31 +350,58 @@ public class PacketParserUtils {
                     break outerloop;
                 }
                 break;
-            case XmlPullParser.TEXT:
+            case TEXT_CHARACTERS:
+                if (startElementJustSeen) {
+                    startElementJustSeen = false;
+                    xml.rightAngleBracket();
+                }
                 xml.escape(parser.getText());
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
             event = parser.next();
         }
         return xml;
     }
 
+    @SuppressWarnings("UnusedVariable")
     private static CharSequence parseContentDepthWithRoundtrip(XmlPullParser parser, int depth, boolean fullNamespaces)
                     throws XmlPullParserException, IOException {
-        StringBuilder sb = new StringBuilder();
-        int event = parser.getEventType();
+        XmlStringBuilder sb = new XmlStringBuilder();
+        XmlPullParser.Event event = parser.getEventType();
+        boolean startElementJustSeen = false;
         outerloop: while (true) {
-            // Only append the text if the parser is not on on an empty element' start tag. Empty elements are reported
-            // twice, so in order to prevent duplication we only add their text when we are on their end tag.
-            if (!(event == XmlPullParser.START_TAG && parser.isEmptyElementTag())) {
+            switch (event) {
+            case START_ELEMENT:
+                if (startElementJustSeen) {
+                    sb.rightAngleBracket();
+                }
+                startElementJustSeen = true;
+                break;
+            case END_ELEMENT:
+                boolean isEmptyElement = false;
+                if (startElementJustSeen) {
+                    isEmptyElement = true;
+                    startElementJustSeen = false;
+                }
+                if (!isEmptyElement) {
+                    String text = parser.getText();
+                    sb.append(text);
+                }
+                if (parser.getDepth() <= depth) {
+                    break outerloop;
+                }
+                break;
+            default:
+                startElementJustSeen = false;
                 CharSequence text = parser.getText();
-                if (event == XmlPullParser.TEXT) {
-                    text = StringUtils.escapeForXmlText(text);
+                if (event == XmlPullParser.Event.TEXT_CHARACTERS) {
+                    text = StringUtils.escapeForXml(text);
                 }
                 sb.append(text);
-            }
-            if (event == XmlPullParser.END_TAG && parser.getDepth() <= depth) {
-                break outerloop;
+                break;
             }
             event = parser.next();
         }
@@ -536,16 +439,14 @@ public class PacketParserUtils {
 
         String language = ParserUtils.getXmlLang(parser);
         if (language != null && !"".equals(language.trim())) {
-        // CHECKSTYLE:OFF
-        	presence.setLanguage(language);
-        // CHECKSTYLE:ON
+            presence.setLanguage(language);
         }
 
         // Parse sub-elements
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String elementName = parser.getName();
                 String namespace = parser.getNamespace();
                 switch (elementName) {
@@ -553,7 +454,7 @@ public class PacketParserUtils {
                     presence.setStatus(parser.nextText());
                     break;
                 case "priority":
-                    int priority = Integer.parseInt(parser.nextText());
+                    Byte priority = ParserUtils.getByteAttributeFromNextText(parser);
                     presence.setPriority(priority);
                     break;
                 case "show":
@@ -587,11 +488,14 @@ public class PacketParserUtils {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         return presence;
@@ -607,9 +511,12 @@ public class PacketParserUtils {
      * @param parser the XML parser, positioned at the start of an IQ packet.
      * @param outerXmlEnvironment the outer XML environment (optional).
      * @return an IQ object.
-     * @throws Exception
+     * @throws XmlPullParserException
+     * @throws XmppStringprepException
+     * @throws IOException
+     * @throws SmackParsingException
      */
-    public static IQ parseIQ(XmlPullParser parser, XmlEnvironment outerXmlEnvironment) throws Exception {
+    public static IQ parseIQ(XmlPullParser parser, XmlEnvironment outerXmlEnvironment) throws XmlPullParserException, XmppStringprepException, IOException, SmackParsingException {
         ParserUtils.assertAtStartTag(parser);
         final int initialDepth = parser.getDepth();
         XmlEnvironment iqXmlEnvironment = XmlEnvironment.from(parser, outerXmlEnvironment);
@@ -622,10 +529,10 @@ public class PacketParserUtils {
         final IQ.Type type = IQ.Type.fromString(parser.getAttributeValue("", "type"));
 
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
 
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String elementName = parser.getName();
                 String namespace = parser.getNamespace();
                 switch (elementName) {
@@ -640,7 +547,7 @@ public class PacketParserUtils {
                             iqPacket = provider.parse(parser, outerXmlEnvironment);
                     }
                     // Note that if we reach this code, it is guranteed that the result IQ contained a child element
-                    // (RFC 6120 § 8.2.3 6) because otherwhise we would have reached the END_TAG first.
+                    // (RFC 6120 § 8.2.3 6) because otherwhise we would have reached the END_ELEMENT first.
                     else {
                         // No Provider found for the IQ stanza, parse it to an UnparsedIQ instance
                         // so that the content of the IQ can be examined later on
@@ -649,11 +556,14 @@ public class PacketParserUtils {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         // Decide what to do when an IQ packet was not understood
@@ -694,15 +604,15 @@ public class PacketParserUtils {
         List<String> mechanisms = new ArrayList<String>();
         boolean done = false;
         while (!done) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
 
-            if (eventType == XmlPullParser.START_TAG) {
+            if (eventType == XmlPullParser.Event.START_ELEMENT) {
                 String elementName = parser.getName();
                 if (elementName.equals("mechanism")) {
                     mechanisms.add(parser.nextText());
                 }
             }
-            else if (eventType == XmlPullParser.END_TAG) {
+            else if (eventType == XmlPullParser.Event.END_ELEMENT) {
                 if (parser.getName().equals("mechanisms")) {
                     done = true;
                 }
@@ -721,14 +631,14 @@ public class PacketParserUtils {
      */
     public static Compress.Feature parseCompressionFeature(XmlPullParser parser)
                     throws IOException, XmlPullParserException {
-        assert (parser.getEventType() == XmlPullParser.START_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.START_ELEMENT);
         String name;
         final int initialDepth = parser.getDepth();
         List<String> methods = new LinkedList<>();
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 name = parser.getName();
                 switch (name) {
                 case "method":
@@ -736,7 +646,7 @@ public class PacketParserUtils {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 name = parser.getName();
                 switch (name) {
                 case Compress.Feature.ELEMENT:
@@ -744,9 +654,13 @@ public class PacketParserUtils {
                         break outerloop;
                     }
                 }
+                break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
-        assert (parser.getEventType() == XmlPullParser.END_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.END_ELEMENT);
         assert (parser.getDepth() == initialDepth);
         return new Compress.Feature(methods);
     }
@@ -782,9 +696,9 @@ public class PacketParserUtils {
         String condition = null;
         Map<String, String> descriptiveTexts = null;
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 if (name.equals("text")) {
                     descriptiveTexts = parseDescriptiveTexts(parser, descriptiveTexts);
@@ -794,11 +708,14 @@ public class PacketParserUtils {
                     condition = parser.getName();
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         return new SASLFailure(condition, descriptiveTexts);
@@ -826,9 +743,9 @@ public class PacketParserUtils {
         String conditionText = null;
         XmlEnvironment streamErrorXmlEnvironment = XmlEnvironment.from(parser, outerXmlEnvironment);
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 String namespace = parser.getNamespace();
                 switch (namespace) {
@@ -841,8 +758,9 @@ public class PacketParserUtils {
                         // If it's not a text element, that is qualified by the StreamError.NAMESPACE,
                         // then it has to be the stream error code
                         condition = StreamError.Condition.fromString(name);
-                        if (!parser.isEmptyElementTag()) {
-                            conditionText = parser.nextText();
+                        conditionText = parser.nextText();
+                        if (conditionText.isEmpty()) {
+                            conditionText = null;
                         }
                         break;
                     }
@@ -852,11 +770,14 @@ public class PacketParserUtils {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
                 break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         return new StreamError(condition, conditionText, descriptiveTexts, extensions);
@@ -888,9 +809,9 @@ public class PacketParserUtils {
         builder.setErrorGenerator(parser.getAttributeValue("", "by"));
 
         outerloop: while (true) {
-            int eventType = parser.next();
+            XmlPullParser.Event eventType = parser.next();
             switch (eventType) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 String namespace = parser.getNamespace();
                 switch (namespace) {
@@ -901,8 +822,9 @@ public class PacketParserUtils {
                         break;
                     default:
                         builder.setCondition(StanzaError.Condition.fromString(name));
-                        if (!parser.isEmptyElementTag()) {
-                            builder.setConditionText(parser.nextText());
+                        String conditionText = parser.nextText();
+                        if (!conditionText.isEmpty()) {
+                            builder.setConditionText(conditionText);
                         }
                         break;
                     }
@@ -911,10 +833,14 @@ public class PacketParserUtils {
                     PacketParserUtils.addExtensionElement(extensions, parser, name, namespace, stanzaErrorXmlEnvironment);
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
+                break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
         builder.setExtensions(extensions).setDescriptiveTexts(descriptiveTexts);
@@ -949,14 +875,14 @@ public class PacketParserUtils {
 
     public static StartTls parseStartTlsFeature(XmlPullParser parser)
                     throws XmlPullParserException, IOException {
-        assert (parser.getEventType() == XmlPullParser.START_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.START_ELEMENT);
         assert (parser.getNamespace().equals(StartTls.NAMESPACE));
         int initalDepth = parser.getDepth();
         boolean required = false;
         outerloop: while (true) {
-            int event = parser.next();
+            XmlPullParser.Event event = parser.next();
             switch (event) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 switch (name) {
                 case "required":
@@ -964,13 +890,17 @@ public class PacketParserUtils {
                     break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initalDepth) {
                     break outerloop;
                 }
+                break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
-        assert (parser.getEventType() == XmlPullParser.END_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.END_ELEMENT);
         return new StartTls(required);
     }
 
@@ -978,14 +908,11 @@ public class PacketParserUtils {
         ParserUtils.assertAtStartTag(parser);
         final int initialDepth = parser.getDepth();
         boolean optional = false;
-        if (parser.isEmptyElementTag()) {
-            return new Session.Feature(optional);
-        }
 
         outerloop: while (true) {
-            int event = parser.next();
+            XmlPullParser.Event event = parser.next();
             switch (event) {
-            case XmlPullParser.START_TAG:
+            case START_ELEMENT:
                 String name = parser.getName();
                 switch (name) {
                     case Session.Feature.OPTIONAL_ELEMENT:
@@ -993,10 +920,14 @@ public class PacketParserUtils {
                         break;
                 }
                 break;
-            case XmlPullParser.END_TAG:
+            case END_ELEMENT:
                 if (parser.getDepth() == initialDepth) {
                     break outerloop;
                 }
+                break;
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
             }
         }
 

smack-core/src/main/java/org/jivesoftware/smack/util/ParserUtils.java

@@ -23,12 +23,15 @@ import java.text.ParseException;
 import java.util.Date;
 import java.util.Locale;
 
-import javax.xml.XMLConstants;
 import javax.xml.namespace.QName;
 
+import org.jivesoftware.smack.datatypes.UInt16;
+import org.jivesoftware.smack.datatypes.UInt32;
 import org.jivesoftware.smack.parsing.SmackParsingException;
 import org.jivesoftware.smack.parsing.SmackParsingException.SmackTextParseException;
 import org.jivesoftware.smack.parsing.SmackParsingException.SmackUriSyntaxParsingException;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jxmpp.jid.EntityBareJid;
 import org.jxmpp.jid.EntityFullJid;
@@ -38,8 +41,6 @@ import org.jxmpp.jid.impl.JidCreate;
 import org.jxmpp.jid.parts.Resourcepart;
 import org.jxmpp.stringprep.XmppStringprepException;
 import org.jxmpp.util.XmppDateTime;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
 
 public class ParserUtils {
 
@@ -49,7 +50,7 @@ public class ParserUtils {
     public static final String JID = "jid";
 
     public static void assertAtStartTag(XmlPullParser parser) throws XmlPullParserException {
-        assert (parser.getEventType() == XmlPullParser.START_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.START_ELEMENT);
     }
 
     public static void assertAtStartTag(XmlPullParser parser, String name) throws XmlPullParserException {
@@ -58,13 +59,13 @@ public class ParserUtils {
     }
 
     public static void assertAtEndTag(XmlPullParser parser) throws XmlPullParserException {
-        assert (parser.getEventType() == XmlPullParser.END_TAG);
+        assert (parser.getEventType() == XmlPullParser.Event.END_ELEMENT);
     }
 
     public static void forwardToEndTagOfDepth(XmlPullParser parser, int depth)
                     throws XmlPullParserException, IOException {
-        int event = parser.getEventType();
-        while (!(event == XmlPullParser.END_TAG && parser.getDepth() == depth)) {
+        XmlPullParser.Event event = parser.getEventType();
+        while (!(event == XmlPullParser.Event.END_ELEMENT && parser.getDepth() == depth)) {
             event = parser.next();
         }
     }
@@ -178,6 +179,11 @@ public class ParserUtils {
         }
     }
 
+    public static Byte getByteAttributeFromNextText(XmlPullParser parser) throws IOException, XmlPullParserException {
+        String nextText = parser.nextText();
+        return Byte.valueOf(nextText);
+    }
+
     public static int getIntegerAttributeOrThrow(XmlPullParser parser, String name, String throwMessage)
                     throws IOException {
         Integer res = getIntegerAttribute(parser, name);
@@ -205,6 +211,14 @@ public class ParserUtils {
         }
     }
 
+    public static UInt16 getUInt16Attribute(XmlPullParser parser, String name) {
+        Integer integer = getIntegerAttribute(parser, name);
+        if (integer == null) {
+            return null;
+        }
+        return UInt16.from(integer);
+    }
+
     public static int getIntegerFromNextText(XmlPullParser parser) throws XmlPullParserException, IOException {
         String intString = parser.nextText();
         return Integer.valueOf(intString);
@@ -227,6 +241,14 @@ public class ParserUtils {
         }
     }
 
+    public static UInt32 getUInt32Attribute(XmlPullParser parser, String name) {
+        Long l = getLongAttribute(parser, name);
+        if (l == null) {
+            return null;
+        }
+        return UInt32.from(l);
+    }
+
     public static double getDoubleFromNextText(XmlPullParser parser) throws XmlPullParserException, IOException {
         String doubleString = parser.nextText();
         return Double.valueOf(doubleString);
@@ -323,13 +345,16 @@ public class ParserUtils {
         return parser.getAttributeValue("http://www.w3.org/XML/1998/namespace", "lang");
     }
 
+    /**
+     * Get the QName of the current element.
+     *
+     * @param parser the parser.
+     * @return the Qname.
+     * @deprecated use {@link XmlPullParser#getQName()} instead.
+     */
+    @Deprecated
+    // TODO: Remove in Smack 4.5
     public static QName getQName(XmlPullParser parser) {
-        String elementName = parser.getName();
-        String prefix = parser.getPrefix();
-        if (prefix == null) {
-            prefix = XMLConstants.DEFAULT_NS_PREFIX;
-        }
-        String namespace = parser.getNamespace();
-        return new QName(namespace, elementName, prefix);
+        return parser.getQName();
     }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/StringUtils.java

@@ -17,7 +17,9 @@
 
 package org.jivesoftware.smack.util;
 
-import java.io.UnsupportedEncodingException;
+import java.io.IOException;
+import java.nio.CharBuffer;
+import java.nio.charset.StandardCharsets;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Random;
@@ -29,7 +31,23 @@ public class StringUtils {
 
     public static final String MD5 = "MD5";
     public static final String SHA1 = "SHA-1";
+
+    /**
+     * Deprecated, do not use.
+     *
+     * @deprecated use StandardCharsets.UTF_8 instead.
+     */
+    // TODO: Remove in Smack 4.5.
+    @Deprecated
     public static final String UTF8 = "UTF-8";
+
+    /**
+     * Deprecated, do not use.
+     *
+     * @deprecated use StandardCharsets.US_ASCII instead.
+     */
+    // TODO: Remove in Smack 4.5.
+    @Deprecated
     public static final String USASCII = "US-ASCII";
 
     public static final String QUOTE_ENCODE = """;
@@ -244,22 +262,13 @@ public class StringUtils {
     }
 
     public static byte[] toUtf8Bytes(String string) {
-        try {
-            return string.getBytes(StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new IllegalStateException("UTF-8 encoding not supported by platform", e);
-        }
+        return string.getBytes(StandardCharsets.UTF_8);
     }
 
     /**
-     * Array of numbers and letters of mixed case. Numbers appear in the list
-     * twice so that there is a more equal chance that a number will be picked.
-     * We can use the array to get a random number or letter by picking a random
-     * array index.
+     * 24 upper case characters from the latin alphabet and numbers without '0' and 'O'.
      */
-    private static final char[] numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyz" +
-                    "ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();
+    private static final char[] UNAMBIGUOUS_NUMBERS_AND_LETTER = "123456789ABCDEFGHIJKLMNPQRSTUVWXYZ".toCharArray();
 
     /**
      * Returns a random String of numbers and letters (lower and upper case)
@@ -278,6 +287,74 @@ public class StringUtils {
         return randomString(length, RandomUtil.RANDOM.get());
     }
 
+    public static String secureOnlineAttackSafeRandomString() {
+        // 34^10 = 2.06e15 possible combinations. Which is enough to protect against online brute force attacks.
+        // See also https://www.grc.com/haystack.htm
+        final int REQUIRED_LENGTH = 10;
+
+        return randomString(RandomUtil.SECURE_RANDOM.get(), UNAMBIGUOUS_NUMBERS_AND_LETTER, REQUIRED_LENGTH);
+    }
+
+    public static String secureUniqueRandomString() {
+        // 34^13 = 8.11e19 possible combinations, which is > 2^64.
+        final int REQUIRED_LENGTH = 13;
+
+        return randomString(RandomUtil.SECURE_RANDOM.get(), UNAMBIGUOUS_NUMBERS_AND_LETTER, REQUIRED_LENGTH);
+    }
+
+    /**
+     * Generate a secure random string with is human readable. The resulting string consists of 24 upper case characters
+     * from the Latin alphabet and numbers without '0' and 'O', grouped into 4-characters chunks, e.g.
+     * "TWNK-KD5Y-MT3T-E1GS-DRDB-KVTW". The characters are randomly selected by a cryptographically secure pseudorandom
+     * number generator (CSPRNG).
+     * <p>
+     * The string can be used a backup "code" for secrets, and is in fact the same as the one backup code specified in
+     * XEP-0373 and the one used by the <a href="https://github.com/open-keychain/open-keychain/wiki/Backups">Backup
+     * Format v2 of OpenKeychain</a>.
+     * </p>
+     *
+     * @see <a href="https://xmpp.org/extensions/xep-0373.html#backup-encryption"> XEP-0373 §5.4 Encrypting the Secret
+     *      Key Backup</a>
+     * @return a human readable secure random string.
+     */
+    public static String secureOfflineAttackSafeRandomString() {
+        // 34^24 = 2^122.10 possible combinations. Which is enough to protect against offline brute force attacks.
+        // See also https://www.grc.com/haystack.htm
+        final int REQUIRED_LENGTH = 24;
+
+        return randomString(RandomUtil.SECURE_RANDOM.get(), UNAMBIGUOUS_NUMBERS_AND_LETTER, REQUIRED_LENGTH);
+    }
+
+    private static final int RANDOM_STRING_CHUNK_SIZE = 4;
+
+    private static String randomString(Random random, char[] alphabet, int numRandomChars) {
+        // The buffer most hold the size of the requested number of random chars and the chunk separators ('-').
+        int bufferSize = numRandomChars + ((numRandomChars - 1) / RANDOM_STRING_CHUNK_SIZE);
+        CharBuffer charBuffer = CharBuffer.allocate(bufferSize);
+
+        try {
+            randomString(charBuffer, random, alphabet, numRandomChars);
+        } catch (IOException e) {
+            // This should never happen if we calcuate the buffer size correctly.
+            throw new AssertionError(e);
+        }
+
+        return charBuffer.flip().toString();
+    }
+
+    private static void randomString(Appendable appendable, Random random, char[] alphabet, int numRandomChars)
+                    throws IOException {
+        for (int randomCharNum = 1; randomCharNum <= numRandomChars; randomCharNum++) {
+            int randomIndex = random.nextInt(alphabet.length);
+            char randomChar = alphabet[randomIndex];
+            appendable.append(randomChar);
+
+            if (randomCharNum % RANDOM_STRING_CHUNK_SIZE == 0 && randomCharNum < numRandomChars) {
+                appendable.append('-');
+            }
+        }
+    }
+
     public static String randomString(final int length) {
         return randomString(length, RandomUtil.SECURE_RANDOM.get());
     }
@@ -287,24 +364,14 @@ public class StringUtils {
             return "";
         }
 
-        byte[] randomBytes = new byte[length];
-        random.nextBytes(randomBytes);
         char[] randomChars = new char[length];
         for (int i = 0; i < length; i++) {
-            randomChars[i] = getPrintableChar(randomBytes[i]);
+            int index = random.nextInt(UNAMBIGUOUS_NUMBERS_AND_LETTER.length);
+            randomChars[i] = UNAMBIGUOUS_NUMBERS_AND_LETTER[index];
         }
         return new String(randomChars);
     }
 
-    private static char getPrintableChar(byte indexByte) {
-        assert (numbersAndLetters.length < Byte.MAX_VALUE * 2);
-
-        // Convert indexByte as it where an unsigned byte by promoting it to int
-        // and masking it with 0xff. Yields results from 0 - 254.
-        int index = indexByte & 0xff;
-        return numbersAndLetters[index % numbersAndLetters.length];
-    }
-
     /**
      * Returns true if CharSequence is not null and is not empty, false otherwise.
      * Examples:

smack-core/src/main/java/org/jivesoftware/smack/util/TLSUtils.java

@@ -64,7 +64,7 @@ public class TLSUtils {
      *
      * @return the given builder
      */
-    public static <B extends ConnectionConfiguration.Builder<B,?>> B setTLSOnly(B builder) {
+    public static <B extends ConnectionConfiguration.Builder<B, ?>> B setTLSOnly(B builder) {
         builder.setEnabledSSLProtocols(new String[] { PROTO_TLSV1_2,  PROTO_TLSV1_1, PROTO_TLSV1 });
         return builder;
     }
@@ -84,7 +84,7 @@ public class TLSUtils {
      *
      * @return the given builder
      */
-    public static <B extends ConnectionConfiguration.Builder<B,?>> B setSSLv3AndTLSOnly(B builder) {
+    public static <B extends ConnectionConfiguration.Builder<B, ?>> B setSSLv3AndTLSOnly(B builder) {
         builder.setEnabledSSLProtocols(new String[] { PROTO_TLSV1_2,  PROTO_TLSV1_1, PROTO_TLSV1, PROTO_SSL3 });
         return builder;
     }
@@ -103,7 +103,7 @@ public class TLSUtils {
      * @throws KeyManagementException
      * @return the given builder.
      */
-    public static <B extends ConnectionConfiguration.Builder<B,?>> B acceptAllCertificates(B builder) throws NoSuchAlgorithmException, KeyManagementException {
+    public static <B extends ConnectionConfiguration.Builder<B, ?>> B acceptAllCertificates(B builder) throws NoSuchAlgorithmException, KeyManagementException {
         SSLContext context = SSLContext.getInstance(TLS);
         context.init(null, new TrustManager[] { new AcceptAllTrustManager() }, new SecureRandom());
         builder.setCustomSSLContext(context);
@@ -130,7 +130,7 @@ public class TLSUtils {
      * @param <B> Type of the ConnectionConfiguration builder.
      * @return the given builder.
      */
-    public static <B extends ConnectionConfiguration.Builder<B,?>> B disableHostnameVerificationForTlsCertificates(B builder) {
+    public static <B extends ConnectionConfiguration.Builder<B, ?>> B disableHostnameVerificationForTlsCertificates(B builder) {
         builder.setHostnameVerifier(DOES_NOT_VERIFY_VERIFIER);
         return builder;
     }

smack-core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java

@@ -269,10 +269,20 @@ public class XmlStringBuilder implements Appendable, CharSequence, Element {
 
     public XmlStringBuilder attribute(String name, Enum<?> value) {
         assert value != null;
+        // TODO: Should use toString() instead of name().
         attribute(name, value.name());
         return this;
     }
 
+    public <E extends Enum<?>> XmlStringBuilder attribute(String name, E value, E implicitDefault) {
+        if (value == null || value == implicitDefault) {
+            return this;
+        }
+
+        attribute(name, value.toString());
+        return this;
+    }
+
     public XmlStringBuilder attribute(String name, int value) {
         assert name != null;
         return attribute(name, String.valueOf(value));
@@ -327,6 +337,13 @@ public class XmlStringBuilder implements Appendable, CharSequence, Element {
         return this;
     }
 
+    public XmlStringBuilder optAttribute(String name, Number number) {
+        if (number != null) {
+            attribute(name, number.toString());
+        }
+        return this;
+    }
+
     /**
      * Add the given attribute if {@code value => 0}.
      *

smack-core/src/main/java/org/jivesoftware/smack/util/XmppElementUtil.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2018 Florian Schmaus
+ * Copyright 2018-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,13 +16,13 @@
  */
 package org.jivesoftware.smack.util;
 
-import org.jivesoftware.smack.packet.FullyQualifiedElement;
+import javax.xml.namespace.QName;
 
-import org.jxmpp.util.XmppStringUtils;
+import org.jivesoftware.smack.packet.FullyQualifiedElement;
 
 public class XmppElementUtil {
 
-    public static String getKeyFor(Class<? extends FullyQualifiedElement> fullyQualifiedElement) {
+    public static QName getQNameFor(Class<? extends FullyQualifiedElement> fullyQualifiedElement) {
         String element, namespace;
         try {
             element = (String) fullyQualifiedElement.getField("ELEMENT").get(null);
@@ -32,14 +32,7 @@ public class XmppElementUtil {
             throw new IllegalArgumentException(e);
         }
 
-        String key = XmppStringUtils.generateKey(element, namespace);
-        return key;
+        return new QName(namespace, element);
     }
 
-    public static String getKeyFor(FullyQualifiedElement fullyQualifiedElement) {
-        String element = fullyQualifiedElement.getElementName();
-        String namespace = fullyQualifiedElement.getNamespace();
-        String key = XmppStringUtils.generateKey(element, namespace);
-        return key;
-    }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base32.java

@@ -19,9 +19,7 @@ package org.jivesoftware.smack.util.stringencoder;
 import java.io.ByteArrayOutputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
-import java.io.UnsupportedEncodingException;
-
-import org.jivesoftware.smack.util.StringUtils;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Base32 string encoding is useful for when filenames case-insensitive filesystems are encoded.
@@ -55,13 +53,8 @@ public class Base32 {
 
     public static String decode(String str) {
         ByteArrayOutputStream bs = new ByteArrayOutputStream();
-        byte[] raw;
-        try {
-            raw = str.getBytes(StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        byte[] raw = str.getBytes(StandardCharsets.UTF_8);
+
         for (int i = 0; i < raw.length; i++) {
             char c = (char) raw[i];
             if (!Character.isWhitespace(c)) {
@@ -114,24 +107,12 @@ public class Base32 {
             }
         }
 
-        String res;
-        try {
-            res = new String(bs.toByteArray(), StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        String res = new String(bs.toByteArray(), StandardCharsets.UTF_8);
         return res;
     }
 
     public static String encode(String str) {
-        byte[] b;
-        try {
-            b = str.getBytes(StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        byte[] b = str.getBytes(StandardCharsets.UTF_8);
         ByteArrayOutputStream os = new ByteArrayOutputStream();
 
         for (int i = 0; i < (b.length + 4) / 5; i++) {
@@ -174,13 +155,7 @@ public class Base32 {
                 os.write(c);
             }
         }
-        String res;
-        try {
-            res = new String(os.toByteArray(), StringUtils.UTF8);
-        }
-        catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        String res = new String(os.toByteArray(), StandardCharsets.UTF_8);
         return res;
     }
 

smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java

@@ -16,10 +16,9 @@
  */
 package org.jivesoftware.smack.util.stringencoder;
 
-import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 
 import org.jivesoftware.smack.util.Objects;
-import org.jivesoftware.smack.util.StringUtils;
 
 public class Base64 {
 
@@ -31,11 +30,7 @@ public class Base64 {
     }
 
     public static final String encode(String string) {
-        try {
-            return encodeToString(string.getBytes(StringUtils.UTF8));
-        } catch (UnsupportedEncodingException e) {
-            throw new IllegalStateException("UTF-8 not supported", e);
-        }
+        return encodeToString(string.getBytes(StandardCharsets.UTF_8));
     }
 
     public static final String encodeToString(byte[] input) {
@@ -56,11 +51,7 @@ public class Base64 {
 
     public static final String decodeToString(String string) {
         byte[] bytes = decode(string);
-        try {
-            return new String(bytes, StringUtils.UTF8);
-        } catch (UnsupportedEncodingException e) {
-            throw new IllegalStateException("UTF-8 not supported", e);
-        }
+        return new String(bytes, StandardCharsets.UTF_8);
     }
 
     // TODO: We really should not mask the IllegalArgumentException. But some unit test depend on this behavior, like
@@ -74,12 +65,7 @@ public class Base64 {
     }
 
     public static final byte[] decode(byte[] input) {
-        String string;
-        try {
-            string = new String(input, StringUtils.USASCII);
-        } catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        String string = new String(input, StandardCharsets.US_ASCII);
         return decode(string);
     }
 

smack-core/src/test/java/org/jivesoftware/smack/StanzaCollectorTest.java

@@ -30,7 +30,7 @@ public class StanzaCollectorTest {
 
     @Test
     public void verifyRollover() throws InterruptedException {
-        TestStanzaCollector collector = new TestStanzaCollector(null, new OKEverything(), 5);
+        StanzaCollector collector = createTestStanzaCollector(null, new OKEverything(), 5);
 
         for (int i = 0; i < 6; i++) {
             Stanza testPacket = new TestPacket(i);
@@ -70,7 +70,7 @@ public class StanzaCollectorTest {
     @Test
     public void verifyThreadSafety() throws InterruptedException {
         final int insertCount = 500;
-        final TestStanzaCollector collector = new TestStanzaCollector(null, new OKEverything(), insertCount);
+        final StanzaCollector collector = createTestStanzaCollector(null, new OKEverything(), insertCount);
 
         final AtomicInteger consumer1Dequeued = new AtomicInteger();
         final AtomicInteger consumer2Dequeued = new AtomicInteger();
@@ -170,10 +170,8 @@ public class StanzaCollectorTest {
 
     }
 
-    static class TestStanzaCollector extends StanzaCollector {
-        protected TestStanzaCollector(XMPPConnection conection, StanzaFilter packetFilter, int size) {
-            super(conection, StanzaCollector.newConfiguration().setStanzaFilter(packetFilter).setSize(size));
-        }
+    private static StanzaCollector createTestStanzaCollector(XMPPConnection connection, StanzaFilter packetFilter, int size) {
+        return new StanzaCollector(connection, StanzaCollector.newConfiguration().setStanzaFilter(packetFilter).setSize(size));
     }
 
     static class TestPacket extends Stanza {

smack-core/src/test/java/org/jivesoftware/smack/compress/packet/FailureTest.java

@@ -16,7 +16,7 @@
  */
 package org.jivesoftware.smack.compress.packet;
 
-import static org.custommonkey.xmlunit.XMLAssert.assertXMLEqual;
+import static org.jivesoftware.smack.test.util.XmlUnitUtils.assertXmlSimilar;
 
 import java.io.IOException;
 
@@ -35,7 +35,7 @@ public class FailureTest {
 
         final String expectedXml = "<failure xmlns='http://jabber.org/protocol/compress'><processing-failed/></failure>";
 
-        assertXMLEqual(expectedXml, xml.toString());
+        assertXmlSimilar(expectedXml, xml.toString());
     }
 
     @Test
@@ -53,6 +53,6 @@ public class FailureTest {
                         + "</error>"
                         + "</failure>";
 
-        assertXMLEqual(expectedXml, xml.toString());
+        assertXmlSimilar(expectedXml, xml.toString());
     }
 }

smack-core/src/test/java/org/jivesoftware/smack/compress/provider/FailureProviderTest.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2018 Florian Schmaus
+ * Copyright 2018-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,9 +22,9 @@ import org.jivesoftware.smack.compress.packet.Failure;
 import org.jivesoftware.smack.packet.StanzaError;
 import org.jivesoftware.smack.packet.StanzaError.Condition;
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 import org.junit.Test;
-import org.xmlpull.v1.XmlPullParser;
 
 public class FailureProviderTest {
 

smack-core/src/test/java/org/jivesoftware/smack/packet/MessageTest.java

@@ -16,7 +16,7 @@
  */
 package org.jivesoftware.smack.packet;
 
-import static org.custommonkey.xmlunit.XMLAssert.assertXMLEqual;
+import static org.jivesoftware.smack.test.util.XmlUnitUtils.assertXmlSimilar;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
@@ -26,8 +26,6 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
-import org.jivesoftware.smack.test.util.XmlUnitUtils;
-
 import org.junit.Test;
 import org.xml.sax.SAXException;
 
@@ -49,7 +47,7 @@ public class MessageTest {
         Message messageTypeInConstructor = new Message(null, Message.Type.chat);
         messageTypeInConstructor.setStanzaId(null);
         assertEquals(type, messageTypeInConstructor.getType());
-        assertXMLEqual(control, messageTypeInConstructor.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, messageTypeInConstructor.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         controlBuilder = new StringBuilder();
         controlBuilder.append("<message")
@@ -62,7 +60,7 @@ public class MessageTest {
         Message messageTypeSet = getNewMessage();
         messageTypeSet.setType(type2);
         assertEquals(type2, messageTypeSet.getType());
-        assertXMLEqual(control, messageTypeSet.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, messageTypeSet.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test(expected = NullPointerException.class)
@@ -87,7 +85,7 @@ public class MessageTest {
         message.setSubject(messageSubject);
 
         assertEquals(messageSubject, message.getSubject());
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test
@@ -106,7 +104,7 @@ public class MessageTest {
         message.setBody(messageBody);
 
         assertEquals(messageBody, message.getBody());
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test
@@ -139,7 +137,7 @@ public class MessageTest {
         message.addBody(null, messageBody1);
         message.addBody(lang2, messageBody2);
         message.addBody(lang3, messageBody3);
-        XmlUnitUtils.assertSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE));
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE));
 
         Collection<String> languages = message.getBodyLanguages();
         List<String> controlLanguages = new ArrayList<>();
@@ -183,7 +181,7 @@ public class MessageTest {
         message.setThread(messageThread);
 
         assertEquals(messageThread, message.getThread());
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test
@@ -201,7 +199,7 @@ public class MessageTest {
         Message message = getNewMessage();
         message.setLanguage(lang);
 
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     private static Message getNewMessage() {

smack-core/src/test/java/org/jivesoftware/smack/packet/PresenceTest.java

@@ -16,14 +16,15 @@
  */
 package org.jivesoftware.smack.packet;
 
-import static org.custommonkey.xmlunit.XMLAssert.assertXMLEqual;
+import static org.jivesoftware.smack.test.util.XmlUnitUtils.assertXmlSimilar;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.IOException;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.xml.sax.SAXException;
 
 public class PresenceTest {
@@ -43,7 +44,7 @@ public class PresenceTest {
         Presence presenceTypeInConstructor = new Presence(type);
         presenceTypeInConstructor.setStanzaId(null);
         assertEquals(type, presenceTypeInConstructor.getType());
-        assertXMLEqual(control, presenceTypeInConstructor.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presenceTypeInConstructor.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         controlBuilder = new StringBuilder();
         controlBuilder.append("<presence")
@@ -56,12 +57,14 @@ public class PresenceTest {
         Presence presenceTypeSet = getNewPresence();
         presenceTypeSet.setType(type2);
         assertEquals(type2, presenceTypeSet.getType());
-        assertXMLEqual(control, presenceTypeSet.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presenceTypeSet.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
-    @Test(expected = NullPointerException.class)
+    @Test
     public void setNullPresenceTypeTest() {
-        getNewPresence().setType(null);
+        assertThrows(IllegalArgumentException.class, () ->
+        getNewPresence().setType(null)
+        );
     }
 
     @Test
@@ -90,7 +93,7 @@ public class PresenceTest {
         presence.setStatus(status);
 
         assertEquals(status, presence.getStatus());
-        assertXMLEqual(control, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test
@@ -109,12 +112,14 @@ public class PresenceTest {
         presence.setPriority(priority);
 
         assertEquals(priority, presence.getPriority());
-        assertXMLEqual(control, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void setIllegalPriorityTest() {
-        getNewPresence().setPriority(Integer.MIN_VALUE);
+        assertThrows(IllegalArgumentException.class, () ->
+        getNewPresence().setPriority(Integer.MIN_VALUE)
+        );
     }
 
     @Test
@@ -142,7 +147,7 @@ public class PresenceTest {
                 mode1);
         presenceModeInConstructor.setStanzaId(null);
         assertEquals(mode1, presenceModeInConstructor.getMode());
-        assertXMLEqual(control, presenceModeInConstructor.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presenceModeInConstructor.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         controlBuilder = new StringBuilder();
         controlBuilder.append("<presence>")
@@ -155,7 +160,7 @@ public class PresenceTest {
         Presence presenceModeSet = getNewPresence();
         presenceModeSet.setMode(mode2);
         assertEquals(mode2, presenceModeSet.getMode());
-        assertXMLEqual(control, presenceModeSet.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presenceModeSet.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test
@@ -183,7 +188,7 @@ public class PresenceTest {
         Presence presence = getNewPresence();
         presence.setLanguage(lang);
 
-        assertXMLEqual(control, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     private static Presence getNewPresence() {

smack-core/src/test/java/org/jivesoftware/smack/packet/StreamErrorTest.java

@@ -18,19 +18,25 @@ package org.jivesoftware.smack.packet;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.fail;
+
+import java.io.IOException;
 
 import org.jivesoftware.smack.packet.StreamError.Condition;
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.test.util.SmackTestUtil;
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
-import org.junit.Test;
-import org.xmlpull.v1.XmlPullParser;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
 
 public class StreamErrorTest {
 
-    @Test
-    public void testParsingOfSimpleStreamError() {
-        StreamError error = null;
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testParsingOfSimpleStreamError(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
         final String xml =
                 // Usually the stream:stream element has more attributes (to, version, ...)
                 // We omit those, since they are not relevant for testing
@@ -39,19 +45,17 @@ public class StreamErrorTest {
                 "<conflict xmlns='urn:ietf:params:xml:ns:xmpp-streams' /> +" +
                 "</stream:error>" +
                 "</stream:stream>";
-        try {
-            XmlPullParser parser = PacketParserUtils.getParserFor(xml, "error");
-            error = PacketParserUtils.parseStreamError(parser);
-        } catch (Exception e) {
-            fail(e.getMessage());
-        }
+
+        XmlPullParser parser = SmackTestUtil.getParserFor(xml, "error", parserKind);
+        StreamError error = PacketParserUtils.parseStreamError(parser);
+
         assertNotNull(error);
         assertEquals(Condition.conflict, error.getCondition());
     }
 
-    @Test
-    public void testParsingOfStreamErrorWithText() {
-        StreamError error = null;
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testParsingOfStreamErrorWithText(SmackTestUtil.XmlPullParserKind parserKind) throws XmlPullParserException, IOException, SmackParsingException {
         final String xml =
                 // Usually the stream:stream element has more attributes (to, version, ...)
                 // We omit those, since they are not relevant for testing
@@ -63,20 +67,19 @@ public class StreamErrorTest {
                 "</text>" +
                 "</stream:error>" +
                 "</stream:stream>";
-        try {
-            XmlPullParser parser = PacketParserUtils.getParserFor(xml, "error");
-            error = PacketParserUtils.parseStreamError(parser);
-        } catch (Exception e) {
-            fail(e.getMessage());
-        }
+
+        XmlPullParser parser = SmackTestUtil.getParserFor(xml, "error", parserKind);
+        StreamError error = PacketParserUtils.parseStreamError(parser);
+
         assertNotNull(error);
         assertEquals(Condition.conflict, error.getCondition());
         assertEquals("Replaced by new connection", error.getDescriptiveText());
     }
 
-    @Test
-    public void testParsingOfStreamErrorWithTextAndOptionalElement() {
-        StreamError error = null;
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testParsingOfStreamErrorWithTextAndOptionalElement(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
         final String xml =
                 // Usually the stream:stream element has more attributes (to, version, ...)
                 // We omit those, since they are not relevant for testing
@@ -91,12 +94,10 @@ public class StreamErrorTest {
                 "</appSpecificElement>" +
                 "</stream:error>" +
                 "</stream:stream>";
-        try {
-            XmlPullParser parser = PacketParserUtils.getParserFor(xml, "error");
-            error = PacketParserUtils.parseStreamError(parser);
-        } catch (Exception e) {
-            fail(e.getMessage());
-        }
+
+        XmlPullParser parser = SmackTestUtil.getParserFor(xml, "error", parserKind);
+        StreamError error = PacketParserUtils.parseStreamError(parser);
+
         assertNotNull(error);
         assertEquals(Condition.conflict, error.getCondition());
         assertEquals("Replaced by new connection", error.getDescriptiveText());
@@ -104,21 +105,20 @@ public class StreamErrorTest {
         assertNotNull(appSpecificElement);
     }
 
-    @Test
-    public void testStreamErrorXmlNotWellFormed() {
-        StreamError error = null;
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testStreamErrorXmlNotWellFormed(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
         final String xml =
                 // Usually the stream:stream element has more attributes (to, version, ...)
                 // We omit those, since they are not relevant for testing
                 "<stream:stream from='im.example.com' id='++TR84Sm6A3hnt3Q065SnAbbk3Y=' xmlns:stream='http://etherx.jabber.org/streams'>" +
                         "<stream:error><xml-not-well-formed xmlns='urn:ietf:params:xml:ns:xmpp-streams'/></stream:error>" +
                         "</stream:stream>";
-        try {
-            XmlPullParser parser = PacketParserUtils.getParserFor(xml, "error");
-            error = PacketParserUtils.parseStreamError(parser);
-        } catch (Exception e) {
-            fail(e.getMessage());
-        }
+
+        XmlPullParser parser = SmackTestUtil.getParserFor(xml, "error", parserKind);
+        StreamError error = PacketParserUtils.parseStreamError(parser);
+
         assertNotNull(error);
         assertEquals(Condition.not_well_formed, error.getCondition());
     }

smack-core/src/test/java/org/jivesoftware/smack/packet/TestIQ.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package org.jivesoftware.smack.packet;
 public class TestIQ extends SimpleIQ {
 
     public TestIQ() {
-        this(null, null);
+        this("https://igniterealtime.org/projects/smack", "test-iq");
     }
 
     public TestIQ(String element, String namespace) {

smack-core/src/test/java/org/jivesoftware/smack/parsing/ParsingExceptionTest.java

@@ -27,11 +27,11 @@ import org.jivesoftware.smack.provider.ExtensionElementProvider;
 import org.jivesoftware.smack.provider.ProviderManager;
 import org.jivesoftware.smack.test.util.TestUtils;
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
-import org.xmlpull.v1.XmlPullParser;
 
 public class ParsingExceptionTest {
 
@@ -39,6 +39,7 @@ public class ParsingExceptionTest {
     "<extension2 xmlns='namespace'>" +
         "<bar node='testNode'>" +
             "<i id='testid1'>" +
+              "text content" +
             "</i>" +
         "</bar>" +
      "</extension2>";
@@ -57,8 +58,7 @@ public class ParsingExceptionTest {
     public void consumeUnparsedInput() throws Exception {
         final String MESSAGE_EXCEPTION_ELEMENT =
                         "<" + ThrowException.ELEMENT + " xmlns='" + ThrowException.NAMESPACE + "'>" +
-                            "<nothingInHere>" +
-                            "</nothingInHere>" +
+                            "<nothingInHere/>" +
                         "</" + ThrowException.ELEMENT + ">";
         XmlPullParser parser = TestUtils.getMessageParser(
                 "<message from='user@server.example' to='francisco@denmark.lit' id='foo'>" +

smack-core/src/test/java/org/jivesoftware/smack/provider/ProviderConfigTest.java

@@ -22,10 +22,10 @@ import java.util.Collection;
 import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.util.FileUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 import org.junit.Assert;
 import org.junit.Test;
-import org.xmlpull.v1.XmlPullParser;
 
 public class ProviderConfigTest {
 

smack-core/src/test/java/org/jivesoftware/smack/provider/ProviderManagerTest.java

@@ -21,9 +21,9 @@ import static org.junit.Assert.assertTrue;
 import org.jivesoftware.smack.SmackConfiguration;
 import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.xml.XmlPullParser;
 
 import org.junit.Test;
-import org.xmlpull.v1.XmlPullParser;
 
 public class ProviderManagerTest {
 

smack-core/src/test/java/org/jivesoftware/smack/sasl/DigestMd5SaslTest.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014-2017 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,10 @@
  */
 package org.jivesoftware.smack.sasl;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -39,14 +39,14 @@ public class DigestMd5SaslTest extends AbstractSaslTest {
         super(saslMechanism);
     }
 
-    protected void runTest(boolean useAuthzid) throws SmackException, InterruptedException, XmppStringprepException, UnsupportedEncodingException {
+    protected void runTest(boolean useAuthzid) throws SmackException, InterruptedException, XmppStringprepException {
         EntityBareJid authzid = null;
         if (useAuthzid) {
             authzid = JidCreate.entityBareFrom("shazbat@xmpp.org");
         }
         saslMechanism.authenticate("florian", "irrelevant", JidCreate.domainBareFrom("xmpp.org"), "secret", authzid, null);
         byte[] response = saslMechanism.evaluateChallenge(challengeBytes);
-        String responseString = new String(response, StringUtils.UTF8);
+        String responseString = new String(response, StandardCharsets.UTF_8);
         String[] responseParts = responseString.split(",");
         Map<String, String> responsePairs = new HashMap<String, String>();
         for (String part : responseParts) {

smack-core/src/test/java/org/jivesoftware/smack/test/util/SmackTestSuite.java

@@ -18,6 +18,7 @@ package org.jivesoftware.smack.test.util;
 
 import java.util.Base64;
 
+import org.jivesoftware.smack.SmackConfiguration;
 import org.jivesoftware.smack.util.stringencoder.Base64.Encoder;
 
 /**
@@ -27,6 +28,7 @@ import org.jivesoftware.smack.util.stringencoder.Base64.Encoder;
 public class SmackTestSuite {
 
     static {
+        SmackConfiguration.getVersion();
         org.jivesoftware.smack.util.stringencoder.Base64.setEncoder(new Encoder() {
 
             @Override

smack-core/src/test/java/org/jivesoftware/smack/test/util/SmackTestUtil.java

@@ -0,0 +1,165 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.test.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.io.StringReader;
+import java.lang.reflect.InvocationTargetException;
+import java.nio.charset.StandardCharsets;
+import java.util.function.Predicate;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.Element;
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.provider.Provider;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+import org.jivesoftware.smack.xml.XmlPullParserFactory;
+import org.jivesoftware.smack.xml.stax.StaxXmlPullParserFactory;
+import org.jivesoftware.smack.xml.xpp3.Xpp3XmlPullParserFactory;
+
+public class SmackTestUtil {
+
+    @SuppressWarnings("ImmutableEnumChecker")
+    public enum XmlPullParserKind {
+        StAX(StaxXmlPullParserFactory.class),
+        XPP3(Xpp3XmlPullParserFactory.class),
+        ;
+
+        public final XmlPullParserFactory factory;
+
+        XmlPullParserKind(Class<? extends XmlPullParserFactory> factoryClass) {
+            try {
+                factory = factoryClass.getDeclaredConstructor().newInstance();
+            }
+            catch (InstantiationException | IllegalAccessException | IllegalArgumentException
+                            | InvocationTargetException | NoSuchMethodException | SecurityException e) {
+                throw new AssertionError(e);
+            }
+        }
+    }
+
+    public static <E extends Element, P extends Provider<E>> E parse(CharSequence xml, Class<P> providerClass, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        P provider = providerClassToProvider(providerClass);
+        return parse(xml, provider, parserKind);
+    }
+
+    public static <E extends Element, P extends Provider<E>> E parse(InputStream inputStream, Class<P> providerClass, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        P provider = providerClassToProvider(providerClass);
+        return parse(inputStream, provider, parserKind);
+    }
+
+    public static <E extends Element, P extends Provider<E>> E parse(Reader reader, Class<P> providerClass, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        P provider = providerClassToProvider(providerClass);
+        return parse(reader, provider, parserKind);
+    }
+
+    public static <E extends Element> E parse(CharSequence xml, Provider<E> provider, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        String xmlString = xml.toString();
+        Reader reader = new StringReader(xmlString);
+        return parse(reader, provider, parserKind);
+    }
+
+    public static <E extends Element> E parse(InputStream inputStream, Provider<E> provider, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
+        return parse(inputStreamReader, provider, parserKind);
+    }
+
+    public static <E extends Element> E parse(Reader reader, Provider<E> provider, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException, SmackParsingException {
+        XmlPullParser parser = getParserFor(reader, parserKind);
+        E element = provider.parse(parser);
+        return element;
+    }
+
+    public static XmlPullParser getParserFor(String xml, XmlPullParserKind parserKind) throws XmlPullParserException, IOException {
+        Reader reader = new StringReader(xml);
+        return getParserFor(reader, parserKind);
+    }
+
+    public static XmlPullParser getParserFor(InputStream inputStream, XmlPullParserKind parserKind) throws XmlPullParserException, IOException {
+        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
+        return getParserFor(inputStreamReader, parserKind);
+    }
+
+    public static XmlPullParser getParserFor(Reader reader, XmlPullParserKind parserKind) throws XmlPullParserException, IOException {
+        XmlPullParser parser = parserKind.factory.newXmlPullParser(reader);
+        forwardParserToStartElement(parser);
+        return parser;
+    }
+
+    public static XmlPullParser getParserFor(String xml, QName startTagQName, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        XmlPullParser parser = getParserFor(xml, parserKind);
+        forwardParserToStartElement(parser, (p) -> p.getQName().equals(startTagQName));
+        return parser;
+    }
+
+    public static XmlPullParser getParserFor(String xml, String startTagLocalpart, XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        XmlPullParser parser = getParserFor(xml, parserKind);
+        forwardParserToStartElement(parser, (p) -> p.getName().equals(startTagLocalpart));
+        return parser;
+    }
+
+    private static <E extends Element, P extends Provider<E>> P providerClassToProvider(Class<P> providerClass) {
+        P provider;
+        // TODO: Consider adding a shortcut in case there is a static INSTANCE field holding an instance of the
+        // requested provider.
+        try {
+            provider = providerClass.getDeclaredConstructor().newInstance();
+        }
+        catch (InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException
+                        | NoSuchMethodException | SecurityException e) {
+            throw new AssertionError(e);
+        }
+        return provider;
+    }
+
+    private static void forwardParserToStartElement(XmlPullParser parser) throws XmlPullParserException, IOException {
+        forwardParserToStartElement(parser, p -> true);
+    }
+
+    private static void forwardParserToStartElement(XmlPullParser parser,
+                    Predicate<XmlPullParser> doneForwarding) throws XmlPullParserException, IOException {
+        outerloop: while (true) {
+            XmlPullParser.Event event = parser.getEventType();
+            switch (event) {
+            case START_ELEMENT:
+                if (doneForwarding.test(parser)) {
+                    break outerloop;
+                }
+                break;
+            case END_DOCUMENT:
+                throw new IllegalArgumentException("Not matching START_ELEMENT found");
+            default:
+                // Catch all for incomplete switch (MissingCasesInEnumSwitch) statement.
+                break;
+            }
+            parser.next();
+        }
+    }
+}

smack-core/src/test/java/org/jivesoftware/smack/test/util/TestUtils.java

@@ -20,14 +20,11 @@ import java.io.IOException;
 import java.io.Reader;
 import java.io.StringReader;
 
-import org.jivesoftware.smack.packet.ExtensionElement;
-import org.jivesoftware.smack.packet.XmlEnvironment;
-import org.jivesoftware.smack.util.PacketParserUtils;
-import org.jivesoftware.smack.util.ParserUtils;
-
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
+import org.jivesoftware.smack.xml.SmackXmlParser;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
+// TODO: Remove this class and replace it with SmackTestUtil.
 public final class TestUtils {
     private TestUtils() {
     }
@@ -52,12 +49,12 @@ public final class TestUtils {
         return getParser(new StringReader(string), startTag);
     }
 
-    public static XmlPullParser getParser(Reader reader, String startTag) {
+    private static XmlPullParser getParser(Reader reader, String startTag) {
         XmlPullParser parser;
         try {
-            parser = PacketParserUtils.newXmppParser(reader);
+            parser = SmackXmlParser.newXmlParser(reader);
             if (startTag == null) {
-                while (parser.getEventType() != XmlPullParser.START_TAG) {
+                while (parser.getEventType() != XmlPullParser.Event.START_ELEMENT) {
                     parser.next();
                 }
                 return parser;
@@ -65,7 +62,7 @@ public final class TestUtils {
             boolean found = false;
 
             while (!found) {
-                if ((parser.next() == XmlPullParser.START_TAG) && parser.getName().equals(startTag))
+                if ((parser.next() == XmlPullParser.Event.START_ELEMENT) && parser.getName().equals(startTag))
                     found = true;
             }
 
@@ -79,17 +76,4 @@ public final class TestUtils {
         return parser;
     }
 
-    public static <EE extends ExtensionElement> EE parseExtensionElement(String elementString)
-                    throws Exception {
-        return parseExtensionElement(getParser(elementString), null);
-    }
-
-    @SuppressWarnings("unchecked")
-    public static <EE extends ExtensionElement> EE parseExtensionElement(XmlPullParser parser, XmlEnvironment outerXmlEnvironment)
-                    throws Exception {
-        ParserUtils.assertAtStartTag(parser);
-        final String elementName = parser.getName();
-        final String namespace = parser.getNamespace();
-        return (EE) PacketParserUtils.parseExtensionElement(elementName, namespace, parser, outerXmlEnvironment);
-    }
 }

smack-core/src/test/java/org/jivesoftware/smack/test/util/XmlUnitUtils.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2014-2018 Florian Schmaus
+ * Copyright 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,24 +16,36 @@
  */
 package org.jivesoftware.smack.test.util;
 
-import static org.custommonkey.xmlunit.XMLAssert.assertXMLEqual;
+import java.io.StringReader;
 
-import java.io.IOException;
+import javax.xml.transform.stream.StreamSource;
 
-import org.custommonkey.xmlunit.Diff;
-import org.custommonkey.xmlunit.examples.RecursiveElementNameAndTextQualifier;
-import org.xml.sax.SAXException;
+import org.xmlunit.assertj.CompareAssert;
+import org.xmlunit.assertj.XmlAssert;
+import org.xmlunit.diff.DefaultNodeMatcher;
+import org.xmlunit.diff.ElementSelectors;
+import org.xmlunit.input.NormalizedSource;
 
+// TODO: Rename this class to XmlAssertUtil
 public class XmlUnitUtils {
 
-    // TOOD: Remove this method.
-    public static void assertSimilar(CharSequence expected, CharSequence actual) throws SAXException, IOException {
-        assertXmlSimilar(expected, actual);
+    public static void assertXmlNotSimilar(CharSequence xmlOne, CharSequence xmlTwo) {
+        normalizedCompare(xmlOne, xmlTwo).areNotSimilar();
     }
 
-    public static void assertXmlSimilar(CharSequence expected, CharSequence actual) throws SAXException, IOException {
-        Diff diff = new Diff(expected.toString(), actual.toString());
-        diff.overrideElementQualifier(new RecursiveElementNameAndTextQualifier());
-        assertXMLEqual(diff, true);
+    public static void assertXmlSimilar(CharSequence expected, CharSequence actual) {
+        normalizedCompare(expected, actual).areSimilar();
+    }
+
+    private static CompareAssert normalizedCompare(CharSequence expectedCharSequence, CharSequence actualCharSequence) {
+        String expectedString = expectedCharSequence.toString();
+        String actualString = actualCharSequence.toString();
+
+        NormalizedSource expected = new NormalizedSource(new StreamSource(new StringReader(expectedString)));
+        NormalizedSource actual = new NormalizedSource(new StreamSource(new StringReader(actualString)));
+        return XmlAssert.assertThat(expected).and(actual)
+                        .ignoreChildNodesOrder()
+                        .withNodeMatcher(new DefaultNodeMatcher(ElementSelectors.byNameAndAllAttributes, ElementSelectors.byNameAndText))
+                        .normalizeWhitespace();
     }
 }

smack-core/src/test/java/org/jivesoftware/smack/util/MemoryLeakTestUtil.java

@@ -16,8 +16,8 @@
  */
 package org.jivesoftware.smack.util;
 
-import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.jupiter.api.Assertions.fail;
 
 import java.lang.ref.PhantomReference;
 import java.lang.ref.Reference;
@@ -51,6 +51,7 @@ public class MemoryLeakTestUtil {
 
     private static final Logger LOGGER = Logger.getLogger(MemoryLeakTestUtil.class.getName());
 
+    @SuppressWarnings("UnusedVariable")
     public static <M extends Manager> void noResourceLeakTest(Function<DummyConnection, M> managerSupplier)
             throws XmppStringprepException, IllegalArgumentException, InterruptedException {
         final int numConnections = 10;
@@ -103,10 +104,27 @@ public class MemoryLeakTestUtil {
     }
 
     private static void assertReferencesQueueSize(ReferenceQueue<?> referenceQueue, int expectedSize) throws IllegalArgumentException, InterruptedException {
-        final int timeout = 60000;
+        final int timeout = 120000;
+        final int maxAttempts = 3;
         for (int itemsRemoved = 0; itemsRemoved < expectedSize; ++itemsRemoved) {
-            Reference<?> reference = referenceQueue.remove(timeout);
-            assertNotNull("No reference found after " + timeout + "ms", reference);
+            int attempt = 0;
+            Reference<?> reference = null;
+            do {
+                reference = referenceQueue.remove(timeout);
+                if (reference != null) {
+                    break;
+                }
+
+                attempt++;
+                String message = "No reference to a gc'ed object found after " + timeout + "ms in the " + attempt
+                                + ". attempt.";
+                if (attempt >= maxAttempts) {
+                    fail(message);
+                }
+
+                LOGGER.warning(message);
+                triggerGarbageCollection();
+            } while (true);
             reference.clear();
         }
 
@@ -119,6 +137,7 @@ public class MemoryLeakTestUtil {
         assertNull(reference);
     }
 
+    @SuppressWarnings("UnusedVariable")
     private static void triggerGarbageCollection() {
         Object object = new Object();
         WeakReference<Object> weakReference = new WeakReference<>(object);
@@ -130,6 +149,8 @@ public class MemoryLeakTestUtil {
                 throw new AssertionError("No observed gargabe collection after " + gcCalls + " calls of System.gc()");
             }
             System.gc();
+            // TODO: Would a Thread.yield() here improve the chances of a full GC? It appears that on some systems we
+            // observe a partial GC here.
             gcCalls++;
         } while (weakReference.get() != null);
 

smack-core/src/test/java/org/jivesoftware/smack/util/NetworkUtil.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2016 Florian Schmaus
+ * Copyright 2016-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,7 +27,7 @@ public class NetworkUtil {
 
     private static final Logger LOGGER = Logger.getLogger(NetworkUtil.class.getName());
 
-    public static ServerSocket getSocketOnLoopback() {
+    public static ServerSocket getSocketOnLoopback() throws IOException {
         final InetAddress loopbackAddress = InetAddress.getLoopbackAddress();
         final int portMin = 1024;
         final int portMax = (1 << 16) - 1;
@@ -40,13 +40,12 @@ public class NetworkUtil {
                 break;
             } catch (BindException e) {
                 LOGGER.log(Level.FINEST, "Could not bind port " + port + ", trying next", e);
-            } catch (IOException e) {
-                throw new IllegalStateException(e);
             }
         }
 
         if (serverSocket == null) {
-            throw new IllegalStateException();
+            throw new IOException("Could not bind any port between " + portMin + " and " + portMax
+                            + " on loopback address" + loopbackAddress);
         }
 
         return serverSocket;

smack-core/src/test/java/org/jivesoftware/smack/util/PacketParserUtilsTest.java

@@ -16,8 +16,8 @@
  */
 package org.jivesoftware.smack.util;
 
-import static org.custommonkey.xmlunit.XMLAssert.assertXMLEqual;
-import static org.custommonkey.xmlunit.XMLAssert.assertXMLNotEqual;
+import static org.jivesoftware.smack.test.util.XmlUnitUtils.assertXmlNotSimilar;
+import static org.jivesoftware.smack.test.util.XmlUnitUtils.assertXmlSimilar;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
@@ -29,6 +29,8 @@ import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Properties;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
 
 import javax.xml.parsers.FactoryConfigurationError;
 import javax.xml.parsers.ParserConfigurationException;
@@ -42,15 +44,17 @@ import org.jivesoftware.smack.packet.StreamOpen;
 import org.jivesoftware.smack.sasl.SASLError;
 import org.jivesoftware.smack.sasl.packet.SaslStreamElements;
 import org.jivesoftware.smack.sasl.packet.SaslStreamElements.SASLFailure;
+import org.jivesoftware.smack.test.util.SmackTestUtil;
 import org.jivesoftware.smack.test.util.TestUtils;
-import org.jivesoftware.smack.test.util.XmlUnitUtils;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import com.jamesmurty.utils.XMLBuilder;
 import org.junit.Ignore;
 import org.junit.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
 import org.xml.sax.SAXException;
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
 
 public class PacketParserUtilsTest {
 
@@ -59,8 +63,9 @@ public class PacketParserUtilsTest {
         outputProperties.put(javax.xml.transform.OutputKeys.OMIT_XML_DECLARATION, "yes");
     }
 
-    @Test
-    public void singleMessageBodyTest() throws Exception {
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void singleMessageBodyTest(SmackTestUtil.XmlPullParserKind parserKind) throws Exception {
         String defaultLanguage = Stanza.getDefaultLanguage();
         String otherLanguage = determineNonDefaultLanguage();
 
@@ -79,13 +84,13 @@ public class PacketParserUtilsTest {
             .asString(outputProperties);
 
         Message message = PacketParserUtils
-                        .parseMessage(PacketParserUtils.getParserFor(control));
+                        .parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertEquals(defaultLanguage, message.getBody());
         assertTrue(message.getBodyLanguages().isEmpty());
         assertEquals(defaultLanguage, message.getBody(defaultLanguage));
         assertNull(message.getBody(otherLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has non-default language, body has no language
         control = XMLBuilder.create("message")
@@ -99,13 +104,13 @@ public class PacketParserUtilsTest {
                 .t(otherLanguage)
             .asString(outputProperties);
 
-        message = PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(control));
+        message = PacketParserUtils.parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertEquals(otherLanguage, message.getBody());
         assertTrue(message.getBodyLanguages().isEmpty());
         assertEquals(otherLanguage, message.getBody(otherLanguage));
         assertNull(message.getBody(defaultLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has no language, body has no language
         control = XMLBuilder.create("message")
@@ -118,13 +123,13 @@ public class PacketParserUtilsTest {
                 .t(defaultLanguage)
             .asString(outputProperties);
 
-        message = PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(control));
+        message = PacketParserUtils.parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertEquals(defaultLanguage, message.getBody());
         assertTrue(message.getBodyLanguages().isEmpty());
         assertEquals(defaultLanguage, message.getBody(null));
         assertNull(message.getBody(otherLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has no language, body has default language
         control = XMLBuilder.create("message")
@@ -138,14 +143,14 @@ public class PacketParserUtilsTest {
                 .t(defaultLanguage)
             .asString(outputProperties);
 
-        message = PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(control));
+        message = PacketParserUtils.parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertNull(message.getBody());
         assertFalse(message.getBodyLanguages().isEmpty());
         assertEquals(defaultLanguage, message.getBody(defaultLanguage));
         assertNull(message.getBody(otherLanguage));
 
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has no language, body has non-default language
         control = XMLBuilder.create("message")
@@ -159,14 +164,14 @@ public class PacketParserUtilsTest {
                 .t(otherLanguage)
             .asString(outputProperties);
 
-        message =  PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(control));
+        message =  PacketParserUtils.parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertNull(message.getBody());
         assertFalse(message.getBodyLanguages().isEmpty());
         assertTrue(message.getBodyLanguages().contains(otherLanguage));
         assertEquals(otherLanguage, message.getBody(otherLanguage));
         assertNull(message.getBody(defaultLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has default language, body has non-default language
         control = XMLBuilder.create("message")
@@ -181,14 +186,14 @@ public class PacketParserUtilsTest {
                 .t(otherLanguage)
             .asString(outputProperties);
 
-        message = PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(control));
+        message = PacketParserUtils.parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertNull(message.getBody());
         assertFalse(message.getBodyLanguages().isEmpty());
         assertTrue(message.getBodyLanguages().contains(otherLanguage));
         assertEquals(otherLanguage, message.getBody(otherLanguage));
         assertNull(message.getBody(defaultLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has non-default language, body has default language
         control = XMLBuilder.create("message")
@@ -203,14 +208,14 @@ public class PacketParserUtilsTest {
                 .t(defaultLanguage)
             .asString(outputProperties);
 
-        message = PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(control));
+        message = PacketParserUtils.parseMessage(SmackTestUtil.getParserFor(control, parserKind));
 
         assertNull(message.getBody());
         assertFalse(message.getBodyLanguages().isEmpty());
         assertTrue(message.getBodyLanguages().contains(defaultLanguage));
         assertEquals(defaultLanguage, message.getBody(defaultLanguage));
         assertNull(message.getBody(otherLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
     }
 
@@ -239,7 +244,7 @@ public class PacketParserUtilsTest {
         assertTrue(message.getSubjectLanguages().isEmpty());
         assertEquals(defaultLanguage, message.getSubject(defaultLanguage));
         assertNull(message.getSubject(otherLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has non-default language, subject has no language
         control = XMLBuilder.create("message")
@@ -258,7 +263,7 @@ public class PacketParserUtilsTest {
         assertTrue(message.getSubjectLanguages().isEmpty());
         assertEquals(otherLanguage, message.getSubject(otherLanguage));
         assertNull(message.getSubject(defaultLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has no language, subject has no language
         control = XMLBuilder.create("message")
@@ -276,7 +281,7 @@ public class PacketParserUtilsTest {
         assertTrue(message.getSubjectLanguages().isEmpty());
         assertEquals(defaultLanguage, message.getSubject(null));
         assertNull(message.getSubject(otherLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has no language, subject has default language
         control = XMLBuilder.create("message")
@@ -295,7 +300,7 @@ public class PacketParserUtilsTest {
         assertEquals(defaultLanguage, message.getSubject(defaultLanguage));
         assertNull(message.getSubject(otherLanguage));
 
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has no language, subject has non-default language
         control = XMLBuilder.create("message")
@@ -315,7 +320,7 @@ public class PacketParserUtilsTest {
         assertTrue(message.getSubjectLanguages().contains(otherLanguage));
         assertEquals(otherLanguage, message.getSubject(otherLanguage));
         assertNull(message.getSubject(defaultLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has default language, subject has non-default language
         control = XMLBuilder.create("message")
@@ -336,7 +341,7 @@ public class PacketParserUtilsTest {
         assertTrue(message.getSubjectLanguages().contains(otherLanguage));
         assertEquals(otherLanguage, message.getSubject(otherLanguage));
         assertNull(message.getSubject(defaultLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has non-default language, subject has default language
         control = XMLBuilder.create("message")
@@ -357,7 +362,7 @@ public class PacketParserUtilsTest {
         assertTrue(message.getSubjectLanguages().contains(defaultLanguage));
         assertEquals(defaultLanguage, message.getSubject(defaultLanguage));
         assertNull(message.getSubject(otherLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
     }
 
@@ -393,7 +398,7 @@ public class PacketParserUtilsTest {
         assertEquals(2, message.getBodies().size());
         assertEquals(1, message.getBodyLanguages().size());
         assertTrue(message.getBodyLanguages().contains(otherLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
 
         // message has non-default language, first body no language, second body default language
         control = XMLBuilder.create("message")
@@ -419,7 +424,7 @@ public class PacketParserUtilsTest {
         assertEquals(2, message.getBodies().size());
         assertEquals(1, message.getBodyLanguages().size());
         assertTrue(message.getBodyLanguages().contains(defaultLanguage));
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
     }
 
     // TODO: Re-enable once we throw an exception on duplicate body elements.
@@ -452,7 +457,7 @@ public class PacketParserUtilsTest {
         assertEquals(defaultLanguage, message.getBody(defaultLanguage));
         assertEquals(1, message.getBodies().size());
         assertEquals(0, message.getBodyLanguages().size());
-        assertXMLNotEqual(control, message.toXML().toString());
+        assertXmlNotSimilar(control, message.toXML().toString());
     }
 
     @Ignore
@@ -510,7 +515,7 @@ public class PacketParserUtilsTest {
         assertEquals(otherLanguage, message.getBody(otherLanguage));
         assertEquals(2, message.getBodies().size());
         assertEquals(1, message.getBodyLanguages().size());
-        assertXMLEqual(control, message.toXML().toString());
+        assertXmlSimilar(control, message.toXML().toString());
     }
 
     @Test
@@ -544,7 +549,7 @@ public class PacketParserUtilsTest {
         assertEquals(2, message.getSubjects().size());
         assertEquals(1, message.getSubjectLanguages().size());
         assertTrue(message.getSubjectLanguages().contains(otherLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has default language, first subject no language, second subject default language
         control = XMLBuilder.create("message")
@@ -568,7 +573,7 @@ public class PacketParserUtilsTest {
         assertEquals(defaultLanguage, message.getSubject(defaultLanguage));
         assertEquals(1, message.getSubjects().size());
         assertEquals(0, message.getSubjectLanguages().size());
-        assertXMLNotEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlNotSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has non-default language, first subject no language, second subject default language
         control = XMLBuilder.create("message")
@@ -593,7 +598,7 @@ public class PacketParserUtilsTest {
         assertEquals(2, message.getSubjects().size());
         assertEquals(1, message.getSubjectLanguages().size());
         assertTrue(message.getSubjectLanguages().contains(defaultLanguage));
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         /*
         // message has no language, first subject no language, second subject default language
@@ -641,7 +646,7 @@ public class PacketParserUtilsTest {
         assertEquals(otherLanguage, message.getSubject(otherLanguage));
         assertEquals(2, message.getSubjects().size());
         assertEquals(1, message.getSubjectLanguages().size());
-        assertXMLEqual(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertXmlSimilar(control, message.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
 
         // message has no language, first subject no language, second subject no language
         control = XMLBuilder.create("message")
@@ -708,13 +713,18 @@ public class PacketParserUtilsTest {
                 .t("Good Message Body")
             .asString(outputProperties);
 
+        // XPP3 writes "end tag", StAX writes "end-tag".
+        Supplier<Stream<String>> expectedContentOfExceptionMessage = () -> Stream.of("end tag", "end-tag");
+
         String invalidControl = validControl.replace("Good Message Body", "Bad </span> Body");
 
         try {
             PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(invalidControl));
             fail("Exception should be thrown");
         } catch (XmlPullParserException e) {
-            assertTrue(e.getMessage().contains("end tag name </span>"));
+            String exceptionMessage = e.getMessage();
+            boolean expectedContentFound = expectedContentOfExceptionMessage.get().anyMatch((expected) -> exceptionMessage.contains(expected));
+            assertTrue(expectedContentFound);
         }
 
         invalidControl = validControl.replace("Good Message Body", "Bad </body> Body");
@@ -723,7 +733,9 @@ public class PacketParserUtilsTest {
             PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(invalidControl));
             fail("Exception should be thrown");
         } catch (XmlPullParserException e) {
-            assertTrue(e.getMessage().contains("end tag name </body>"));
+            String exceptionMessage = e.getMessage();
+            boolean expectedContentFound = expectedContentOfExceptionMessage.get().anyMatch((expected) -> exceptionMessage.contains(expected));
+            assertTrue(expectedContentFound);
         }
 
         invalidControl = validControl.replace("Good Message Body", "Bad </message> Body");
@@ -732,9 +744,10 @@ public class PacketParserUtilsTest {
             PacketParserUtils.parseMessage(PacketParserUtils.getParserFor(invalidControl));
             fail("Exception should be thrown");
         } catch (XmlPullParserException e) {
-            assertTrue(e.getMessage().contains("end tag name </message>"));
+            String exceptionMessage = e.getMessage();
+            boolean expectedContentFound = expectedContentOfExceptionMessage.get().anyMatch((expected) -> exceptionMessage.contains(expected));
+            assertTrue(expectedContentFound);
         }
-
     }
 
     @Test
@@ -763,58 +776,52 @@ public class PacketParserUtilsTest {
             .asString(outputProperties);
 
         Stanza message = PacketParserUtils.parseStanza(control);
-        XmlUnitUtils.assertSimilar(control, message.toXML());
+        assertXmlSimilar(control, message.toXML());
     }
 
     @Test
     public void validateSimplePresence() throws Exception {
-        // CHECKSTYLE:OFF
-    	String stanza = "<presence from='juliet@example.com/balcony' to='romeo@example.net'/>";
+        String stanza = "<presence from='juliet@example.com/balcony' to='romeo@example.net'/>";
 
-    	Presence presence = PacketParserUtils.parsePresence(PacketParserUtils.getParserFor(stanza));
+        Presence presence = PacketParserUtils.parsePresence(PacketParserUtils.getParserFor(stanza));
 
-    	assertXMLEqual(stanza, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
-        // CHECKSTYLE:ON
+        assertXmlSimilar(stanza, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
     }
 
     @Test
     public void validatePresenceProbe() throws Exception {
-        // CHECKSTYLE:OFF
-    	String stanza = "<presence from='mercutio@example.com' id='xv291f38' to='juliet@example.com' type='unsubscribed'/>";
+        String stanza = "<presence from='mercutio@example.com' id='xv291f38' to='juliet@example.com' type='unsubscribed'/>";
 
-    	Presence presence = PacketParserUtils.parsePresence(PacketParserUtils.getParserFor(stanza));
+        Presence presence = PacketParserUtils.parsePresence(PacketParserUtils.getParserFor(stanza));
 
-    	assertXMLEqual(stanza, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
-    	assertEquals(Presence.Type.unsubscribed, presence.getType());
-        // CHECKSTYLE:ON
+        assertXmlSimilar(stanza, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertEquals(Presence.Type.unsubscribed, presence.getType());
     }
 
     @Test
     public void validatePresenceOptionalElements() throws Exception {
-        // CHECKSTYLE:OFF
-    	String stanza = "<presence xml:lang='en' type='unsubscribed'>"
-    			+ "<show>dnd</show>"
-    			+ "<status>Wooing Juliet</status>"
-    			+ "<priority>1</priority>"
-    			+ "</presence>";
+        String stanza = "<presence xml:lang='en' type='unsubscribed'>"
+                + "<show>dnd</show>"
+                + "<status>Wooing Juliet</status>"
+                + "<priority>1</priority>"
+                + "</presence>";
 
-    	Presence presence = PacketParserUtils.parsePresence(PacketParserUtils.getParserFor(stanza));
-    	assertXMLEqual(stanza, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
-    	assertEquals(Presence.Type.unsubscribed, presence.getType());
-    	assertEquals("dnd", presence.getMode().name());
-    	assertEquals("en", presence.getLanguage());
-    	assertEquals("Wooing Juliet", presence.getStatus());
-    	assertEquals(1, presence.getPriority());
-        // CHECKSTYLE:ON
+        Presence presence = PacketParserUtils.parsePresence(PacketParserUtils.getParserFor(stanza));
+        assertXmlSimilar(stanza, presence.toXML(StreamOpen.CLIENT_NAMESPACE).toString());
+        assertEquals(Presence.Type.unsubscribed, presence.getType());
+        assertEquals("dnd", presence.getMode().name());
+        assertEquals("en", presence.getLanguage());
+        assertEquals("Wooing Juliet", presence.getStatus());
+        assertEquals(1, presence.getPriority());
     }
 
-    @Test
-    public void parseContentDepthTest() throws Exception {
-        final String stanza = "<iq type='result' to='foo@bar.com' from='baz.com' id='42'/>";
-        XmlPullParser parser = TestUtils.getParser(stanza, "iq");
-        CharSequence content = PacketParserUtils.parseContent(parser);
-        assertEquals("", content.toString());
-    }
+//    @Test
+//    public void parseContentDepthTest() throws Exception {
+//        final String stanza = "<iq type='result' to='foo@bar.com' from='baz.com' id='42'/>";
+//        XmlPullParser parser = TestUtils.getParser(stanza, "iq");
+//        CharSequence content = PacketParserUtils.parseContent(parser);
+//        assertEquals("", content.toString());
+//    }
 
     @Test
     public void parseElementMultipleNamespace()
@@ -830,7 +837,7 @@ public class PacketParserUtilsTest {
         // @formatter:on
         XmlPullParser parser = TestUtils.getParser(stanza, "outer");
         CharSequence result = PacketParserUtils.parseElement(parser, true);
-        assertXMLEqual(stanza, result.toString());
+        assertXmlSimilar(stanza, result.toString());
     }
 
     @Test
@@ -843,7 +850,7 @@ public class PacketParserUtilsTest {
         // @formatter:on
         XmlPullParser parser = TestUtils.getParser(saslFailureString, SASLFailure.ELEMENT);
         SASLFailure saslFailure = PacketParserUtils.parseSASLFailure(parser);
-        assertXMLEqual(saslFailureString, saslFailure.toString());
+        assertXmlSimilar(saslFailureString, saslFailure.toString());
     }
 
     @Test
@@ -865,7 +872,7 @@ public class PacketParserUtilsTest {
         // @formatter:on
         XmlPullParser parser = TestUtils.getParser(saslFailureString, SASLFailure.ELEMENT);
         SASLFailure saslFailure = PacketParserUtils.parseSASLFailure(parser);
-        XmlUnitUtils.assertSimilar(saslFailureString, saslFailure.toXML(StreamOpen.CLIENT_NAMESPACE));
+        assertXmlSimilar(saslFailureString, saslFailure.toXML(StreamOpen.CLIENT_NAMESPACE));
     }
 
     @SuppressWarnings("ReferenceEquality")
@@ -909,7 +916,7 @@ public class PacketParserUtilsTest {
                 .element("internal-server-error", StanzaError.ERROR_CONDITION_AND_TEXT_NAMESPACE).up()
                 .element("text", StanzaError.ERROR_CONDITION_AND_TEXT_NAMESPACE).t(text).up()
                 .asString();
-        XmlUnitUtils.assertSimilar(errorXml, error.toXML(StreamOpen.CLIENT_NAMESPACE));
+        assertXmlSimilar(errorXml, error.toXML(StreamOpen.CLIENT_NAMESPACE));
     }
 
     @Test

smack-core/src/test/java/org/jivesoftware/smack/util/StringUtilsTest.java

@@ -21,7 +21,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
-import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 
 import org.junit.Test;
 
@@ -31,11 +31,9 @@ import org.junit.Test;
 public class StringUtilsTest  {
     @Test
     public void testEscapeForXml() {
-        String input = null;
-
         assertNull(StringUtils.escapeForXml(null));
 
-        input = "<b>";
+        String input = "<b>";
         assertCharSequenceEquals("&lt;b&gt;", StringUtils.escapeForXml(input));
 
         input = "\"";
@@ -74,15 +72,15 @@ public class StringUtilsTest  {
     }
 
     @Test
-    public void testEncodeHex() throws UnsupportedEncodingException {
+    public void testEncodeHex() {
         String input = "";
         String output = "";
-        assertEquals(new String(StringUtils.encodeHex(input.getBytes(StringUtils.UTF8))),
+        assertEquals(new String(StringUtils.encodeHex(input.getBytes(StandardCharsets.UTF_8))),
                 output);
 
         input = "foo bar 123";
         output = "666f6f2062617220313233";
-        assertEquals(new String(StringUtils.encodeHex(input.getBytes(StringUtils.UTF8))),
+        assertEquals(new String(StringUtils.encodeHex(input.getBytes(StandardCharsets.UTF_8))),
                 output);
     }
 

smack-core/src/test/java/org/jivesoftware/smack/xml/XmlPullParserTest.java

@@ -0,0 +1,231 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.xml;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
+import java.util.stream.Stream;
+
+import javax.xml.XMLConstants;
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.test.util.SmackTestUtil;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+
+public class XmlPullParserTest {
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testSimpleEmptyElement(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        Reader reader = new StringReader("<empty-element/>");
+        XmlPullParser parser = parserKind.factory.newXmlPullParser(reader);
+
+        assertEquals(XmlPullParser.Event.START_DOCUMENT, parser.getEventType());
+        assertEquals(XmlPullParser.Event.START_ELEMENT, parser.next());
+        QName qname = parser.getQName();
+        assertEquals(qname.getLocalPart(), "empty-element");
+        assertEquals(qname.getPrefix(), XMLConstants.DEFAULT_NS_PREFIX);
+        assertEquals(qname.getNamespaceURI(), XMLConstants.NULL_NS_URI);
+        assertEquals(XmlPullParser.Event.END_ELEMENT, parser.next());
+        assertEquals(XmlPullParser.Event.END_DOCUMENT, parser.next());
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testQNameSimpleElement(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String simpleElement = "<outer-element xmlns='outer-namespace'><inner-element/></outer-element>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(simpleElement, parserKind);
+        QName qname = parser.getQName();
+        assertEquals("outer-element", qname.getLocalPart());
+        assertEquals("outer-namespace", qname.getNamespaceURI());
+        assertEquals(XmlPullParser.Event.START_ELEMENT, parser.next());
+        qname = parser.getQName();
+        assertEquals("inner-element", qname.getLocalPart());
+        assertEquals("outer-namespace", qname.getNamespaceURI());
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testQNamePrefixElement(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String prefixElement = "<outer-element xmlns='outer-namespace' xmlns:inner-prefix='inner-namespace'><inner-prefix:inner-element></outer-element>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(prefixElement, parserKind);
+        QName qname = parser.getQName();
+        assertEquals("outer-element", qname.getLocalPart());
+        assertEquals("outer-namespace", qname.getNamespaceURI());
+        assertEquals(XmlPullParser.Event.START_ELEMENT, parser.next());
+        qname = parser.getQName();
+        assertEquals("inner-element", qname.getLocalPart());
+        assertEquals("inner-namespace", qname.getNamespaceURI());
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testAttributesElementWithOneAttribute(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String elementWithOneAttribute = "<element attribute-one='attribute-one-value'/>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(elementWithOneAttribute, parserKind);
+        assertAttributeHolds(parser, 0, "attribute-one", "", "");
+        assertThrows(NullPointerException.class, () ->
+            assertAttributeHolds(parser, 1, "attribute-one", "", ""));
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testAttributesNamespacedElementWithOneAttribute(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String namespacedElementWithOneAttribute = "<element xmlns='element-namespace' attribute-one='attribute-one-value'/>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(namespacedElementWithOneAttribute, parserKind);
+        assertAttributeHolds(parser, 0, "attribute-one", "", "");
+        assertThrows(NullPointerException.class, () ->
+            assertAttributeHolds(parser, 1, "attribute-one", "", ""));
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testAttributesNamespacedElementWithOneNamespacedAttribute(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String namespacedElementWithOneNamespacedAttribute = "<element xmlns='element-namespace' xmlns:attribute-namespace='attribute-namespace-value' attribute-namespace:attribute-one='attribute-one-value'/>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(namespacedElementWithOneNamespacedAttribute, parserKind);
+        assertAttributeHolds(parser, 0, "attribute-one", "attribute-namespace", "attribute-namespace-value");
+        assertThrows(NullPointerException.class, () ->
+            assertAttributeHolds(parser, 1, "attribute-one", "", ""));
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testNamespacedAttributes(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String element = "<element xmlns:attr='attribute-namespace' attr:attributeOneName='attributeOneValue'/>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(element, parserKind);
+        assertEquals(1, parser.getAttributeCount());
+
+        assertEquals("attributeOneName", parser.getAttributeName(0));
+        assertEquals("attr", parser.getAttributePrefix(0));
+        assertEquals("attribute-namespace", parser.getAttributeNamespace(0));
+        QName attributeZeroQname = parser.getAttributeQName(0);
+        assertEquals("attributeOneName", attributeZeroQname.getLocalPart());
+        assertEquals("attr", attributeZeroQname.getPrefix());
+        assertEquals("attribute-namespace", attributeZeroQname.getNamespaceURI());
+
+        // Test how parser handle non-existent attributes.
+        assertNull(parser.getAttributeName(1));
+        assertNull(parser.getAttributePrefix(1));
+        assertNull(parser.getAttributeNamespace(1));
+        QName attributeOneQname = parser.getAttributeQName(1);
+        assertNull(attributeOneQname);
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testAttributeType(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String element = "<element xmlns:attr='attribute-namespace' attr:attributeOneName='attributeOneValue'/>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(element, parserKind);
+
+        assertEquals("CDATA", parser.getAttributeType(0));
+
+        assertNull(parser.getAttributeType(1));
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testNextText(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        XmlPullParser parser;
+
+        String simpleElement = "<element>Element text</element>";
+        parser = SmackTestUtil.getParserFor(simpleElement, parserKind);
+        assertEquals("Element text", parser.nextText());
+
+        String complexElement = "<outer-elment><element1>Element 1 &apos; text</element1><element2>Element 2 text</element2></outer-element>";
+        parser = SmackTestUtil.getParserFor(complexElement, parserKind);
+        assertEquals(XmlPullParser.Event.START_ELEMENT, parser.next());
+        assertEquals("element1", parser.getName());
+        assertEquals(0, parser.getAttributeCount());
+        assertEquals("Element 1 ' text", parser.nextText());
+
+        assertEquals(XmlPullParser.Event.START_ELEMENT, parser.next());
+        assertEquals("element2", parser.getName());
+        assertEquals(0, parser.getAttributeCount());
+        assertEquals("Element 2 text", parser.nextText());
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testNextTextMixedContent(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String element = "<element>Mixed content element text<inner-element>Inner element text</inner-element></element>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(element, parserKind);
+        assertThrows(XmlPullParserException.class, () -> parser.nextText());
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testNextTextOnEndElement(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String element = "<element>Element text</element>";
+        XmlPullParser parser = SmackTestUtil.getParserFor(element, parserKind);
+        assertEquals(XmlPullParser.Event.START_ELEMENT, parser.getEventType());
+        assertEquals(XmlPullParser.Event.TEXT_CHARACTERS, parser.next());
+        assertEquals(XmlPullParser.Event.END_ELEMENT, parser.next());
+        assertThrows(XmlPullParserException.class, () -> parser.nextText());
+    }
+
+    @ParameterizedTest
+    @EnumSource(SmackTestUtil.XmlPullParserKind.class)
+    public void testNextTextOnEmptyElement(SmackTestUtil.XmlPullParserKind parserKind)
+                    throws XmlPullParserException, IOException {
+        String[] emptyElementStream = Stream.of().toArray(String[]::new);
+        for (String emptyElement : emptyElementStream) {
+            XmlPullParser parser = SmackTestUtil.getParserFor(emptyElement, parserKind);
+            assertEquals(XmlPullParser.Event.START_ELEMENT, parser.getEventType());
+            assertEquals("", parser.nextText());
+        }
+    }
+
+    private static void assertAttributeHolds(XmlPullParser parser, int attributeIndex, String expectedLocalpart,
+                    String expectedPrefix, String expectedNamespace) {
+        QName qname = parser.getAttributeQName(attributeIndex);
+        String qnameNamespaceUri = qname.getNamespaceURI();
+
+        assertEquals(expectedLocalpart, qname.getLocalPart());
+        assertEquals(expectedPrefix, qname.getPrefix());
+        assertEquals(expectedNamespace, qnameNamespaceUri);
+
+        assertEquals(qname.getLocalPart(), parser.getAttributeName(attributeIndex));
+        assertEquals(qname.getPrefix(), parser.getAttributePrefix(attributeIndex));
+
+        final String expectedGetAttributeNamespace;
+        if (qnameNamespaceUri.equals(XMLConstants.NULL_NS_URI)) {
+            expectedGetAttributeNamespace = null;
+        }
+        else {
+            expectedGetAttributeNamespace = qnameNamespaceUri;
+        }
+        assertEquals(expectedGetAttributeNamespace, parser.getAttributeNamespace(attributeIndex));
+    }
+}

smack-debug/src/main/java/org/jivesoftware/smackx/debugger/EnhancedDebugger.java

@@ -257,11 +257,9 @@ public class EnhancedDebugger extends SmackDebugger {
                 new DefaultTableModel(
                         new Object[] {"Hide", "Timestamp", "", "", "Message", "Id", "Type", "To", "From"},
                         0) {
-                    // CHECKSTYLE:OFF
-        			private static final long serialVersionUID = 8136121224474217264L;
-					@Override
+                    private static final long serialVersionUID = 8136121224474217264L;
+                    @Override
                     public boolean isCellEditable(int rowIndex, int mColIndex) {
-                    // CHECKSTYLE:ON
                         return false;
                     }
 
@@ -689,11 +687,9 @@ public class EnhancedDebugger extends SmackDebugger {
                 new DefaultTableModel(new Object[][] { {"IQ", 0, 0}, {"Message", 0, 0},
                         {"Presence", 0, 0}, {"Other", 0, 0}, {"Total", 0, 0}},
                         new Object[] {"Type", "Received", "Sent"}) {
-                    // CHECKSTYLE:OFF
-        			private static final long serialVersionUID = -6793886085109589269L;
-					@Override
+                    private static final long serialVersionUID = -6793886085109589269L;
+                    @Override
                     public boolean isCellEditable(int rowIndex, int mColIndex) {
-                    // CHECKSTYLE:ON
                         return false;
                     }
                 };

smack-debug/src/main/java/org/jivesoftware/smackx/debugger/EnhancedDebuggerWindow.java

@@ -346,6 +346,7 @@ public final class EnhancedDebuggerWindow {
      *
      * @param evt the event that indicates that the root window is closing
      */
+    @SuppressWarnings("UnusedVariable")
     private synchronized void rootWindowClosing(WindowEvent evt) {
         // Notify to all the debuggers to stop debugging
         for (EnhancedDebugger debugger : debuggers) {

smack-experimental/src/main/java/org/jivesoftware/smackx/carbons/provider/CarbonManagerProvider.java

@@ -21,15 +21,14 @@ import java.io.IOException;
 import org.jivesoftware.smack.packet.XmlEnvironment;
 import org.jivesoftware.smack.parsing.SmackParsingException;
 import org.jivesoftware.smack.provider.ExtensionElementProvider;
+import org.jivesoftware.smack.xml.XmlPullParser;
+import org.jivesoftware.smack.xml.XmlPullParserException;
 
 import org.jivesoftware.smackx.carbons.packet.CarbonExtension;
 import org.jivesoftware.smackx.carbons.packet.CarbonExtension.Direction;
 import org.jivesoftware.smackx.forward.packet.Forwarded;
 import org.jivesoftware.smackx.forward.provider.ForwardedProvider;
 
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlPullParserException;
-
 /**
  * This class implements the {@link ExtensionElementProvider} to parse
  * carbon copied messages from a packet.  It will return a {@link CarbonExtension} stanza extension.
@@ -48,11 +47,11 @@ public class CarbonManagerProvider extends ExtensionElementProvider<CarbonExtens
 
         boolean done = false;
         while (!done) {
-            int eventType = parser.next();
-            if (eventType == XmlPullParser.START_TAG && parser.getName().equals("forwarded")) {
+            XmlPullParser.Event eventType = parser.next();
+            if (eventType == XmlPullParser.Event.START_ELEMENT && parser.getName().equals("forwarded")) {
                 fwd = FORWARDED_PROVIDER.parse(parser);
             }
-            else if (eventType == XmlPullParser.END_TAG && dir == Direction.valueOf(parser.getName()))
+            else if (eventType == XmlPullParser.Event.END_ELEMENT && dir == Direction.valueOf(parser.getName()))
                 done = true;
         }
         if (fwd == null) {

smack-experimental/src/main/java/org/jivesoftware/smackx/chat_markers/ChatMarkersManager.java

@@ -42,6 +42,7 @@ import org.jivesoftware.smack.filter.StanzaExtensionFilter;
 import org.jivesoftware.smack.filter.StanzaFilter;
 import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.packet.Stanza;
+
 import org.jivesoftware.smackx.chat_markers.element.ChatMarkersElements;
 import org.jivesoftware.smackx.chat_markers.filter.ChatMarkersFilter;
 import org.jivesoftware.smackx.chat_markers.filter.EligibleForChatMarkerFilter;

smack-experimental/src/main/java/org/jivesoftware/smackx/chat_markers/element/ChatMarkersElements.java

@@ -20,6 +20,7 @@ import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmlStringBuilder;
+
 import org.jivesoftware.smackx.chat_markers.ChatMarkersState;
 
 /**

smack-experimental/src/main/java/org/jivesoftware/smackx/chat_markers/filter/ChatMarkersFilter.java

@@ -18,6 +18,7 @@ package org.jivesoftware.smackx.chat_markers.filter;
 
 import org.jivesoftware.smack.filter.StanzaExtensionFilter;
 import org.jivesoftware.smack.filter.StanzaFilter;
+
 import org.jivesoftware.smackx.chat_markers.element.ChatMarkersElements;
 
 /**

smack-experimental/src/main/java/org/jivesoftware/smackx/chat_markers/filter/EligibleForChatMarkerFilter.java

@@ -19,6 +19,7 @@ package org.jivesoftware.smackx.chat_markers.filter;
 import org.jivesoftware.smack.filter.StanzaExtensionFilter;
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.Stanza;
+
 import org.jivesoftware.smackx.chatstates.ChatState;
 import org.jivesoftware.smackx.chatstates.ChatStateManager;