Do not use a reflection based initializer for core elements

like Message.Body from smack-core.

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

@@ -1,27 +0,0 @@
-/**
- *
- * Copyright 2018 Paul Schaub.
- *
- * 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;
-
-import org.jivesoftware.smack.initializer.UrlInitializer;
-
-public class CoreInitializer extends UrlInitializer {
-
-    @Override
-    protected String getProvidersUri() {
-        return "classpath:org.jivesoftware.smack/core.providers";
-    }
-}

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

@@ -29,7 +29,9 @@ import java.util.logging.Logger;
 import org.jivesoftware.smack.compression.Java7ZlibInputOutputStream;
 import org.jivesoftware.smack.initializer.SmackInitializer;
 import org.jivesoftware.smack.packet.Bind;
+import org.jivesoftware.smack.packet.Message.Body;
 import org.jivesoftware.smack.provider.BindIQProvider;
+import org.jivesoftware.smack.provider.BodyElementProvider;
 import org.jivesoftware.smack.provider.ProviderManager;
 import org.jivesoftware.smack.sasl.core.SASLAnonymous;
 import org.jivesoftware.smack.sasl.core.SASLXOauth2Mechanism;
@@ -116,6 +118,7 @@ public final class SmackInitialization {
         SASLAuthentication.registerSASLMechanism(new SASLAnonymous());
 
         ProviderManager.addIQProvider(Bind.ELEMENT, Bind.NAMESPACE, new BindIQProvider());
+        ProviderManager.addExtensionProvider(Body.ELEMENT, Body.NAMESPACE, new BodyElementProvider());
 
         SmackConfiguration.smackInitialized = true;
     }

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

@@ -28,6 +28,7 @@ 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;
@@ -71,6 +72,9 @@ public class PacketParserUtils {
     public static final boolean XML_PULL_PARSER_SUPPORTS_ROUNDTRIP;
 
     static {
+        // Ensure that Smack is initialized.
+        SmackConfiguration.getVersion();
+
         XmlPullParser xmlPullParser;
         boolean roundtrip = false;
         try {

smack-core/src/main/resources/org.jivesoftware.smack/core.providers

@@ -1,9 +0,0 @@
-<?xml version="1.0"?>
-<!-- Providers for core elements -->
-<smackProviders>
-    <extensionProvider>
-      <elementName>body</elementName>
-      <namespace>jabber:client</namespace>
-      <className>org.jivesoftware.smack.provider.BodyElementProvider</className>
-    </extensionProvider>
-</smackProviders>

smack-core/src/main/resources/org.jivesoftware.smack/smack-config.xml

@@ -5,7 +5,6 @@
     <startupClasses>
         <className>org.jivesoftware.smack.initializer.VmArgInitializer</className>
         <className>org.jivesoftware.smack.ReconnectionManager</className>
-        <className>org.jivesoftware.smack.CoreInitializer</className>
     </startupClasses>
 
     <optionalStartupClasses>