Remove XmlLangStanza

since all stanza types could have 'xml:lang' defined as top-level
stream element attribute.

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

@@ -51,7 +51,7 @@ import org.jivesoftware.smack.util.XmlStringBuilder;
  *
  * @author Matt Tucker
  */
-public class Message extends XmlLangStanza {
+public class Message extends Packet {
 
     public static final String ELEMENT = "message";
     public static final String BODY = "body";
@@ -396,7 +396,6 @@ public class Message extends XmlLangStanza {
     public XmlStringBuilder toXML() {
         XmlStringBuilder buf = new XmlStringBuilder();
         buf.halfOpenElement(ELEMENT);
-        buf.xmllangAttribute(language);
         addCommonAttributes(buf);
         if (type != Type.normal) {
             buf.attribute("type", type);

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

@@ -61,6 +61,18 @@ public abstract class Packet extends TopLevelStreamElement {
 
     private XMPPError error = null;
 
+    /**
+     * Optional value of the 'xml:lang' attribute of the outermost element of
+     * the stanza.
+     * <p>
+     * Such an attribute is defined for all stanza types. For IQ, see for
+     * example XEP-50 3.7:
+     * "The requester SHOULD provide its locale information using the "xml:lang
+     * " attribute on either the <iq/> (RECOMMENDED) or <command/> element."
+     * </p>
+     */
+    protected String language;
+
     public Packet() {
         this(prefix + Long.toString(id.incrementAndGet()));
     }
@@ -165,6 +177,24 @@ public abstract class Packet extends TopLevelStreamElement {
         this.error = error;
     }
 
+    /**
+     * Returns the xml:lang of this Stanza, or null if one has not been set.
+     *
+     * @return the xml:lang of this Stanza, or null.
+     */
+    public String getLanguage() {
+        return language;
+    }
+
+    /**
+     * Sets the xml:lang of this Stanza.
+     *
+     * @param language the xml:lang of this Stanza.
+     */
+    public void setLanguage(String language) {
+        this.language = language;
+    }
+
     /**
      * Returns an unmodifiable collection of the packet extensions attached to the packet.
      *
@@ -305,7 +335,7 @@ public abstract class Packet extends TopLevelStreamElement {
     }
 
     /**
-     * Add to, from and id attributes
+     * Add to, from, id and 'xml:lang' attributes
      *
      * @param xml
      */
@@ -313,5 +343,6 @@ public abstract class Packet extends TopLevelStreamElement {
         xml.optAttribute("id", getPacketID());
         xml.optAttribute("to", getTo());
         xml.optAttribute("from", getFrom());
+        xml.xmllangAttribute(getLanguage());
     }
 }

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

@@ -55,7 +55,7 @@ import org.jivesoftware.smack.util.XmlStringBuilder;
  * @see RosterPacket
  * @author Matt Tucker
  */
-public class Presence extends XmlLangStanza {
+public class Presence extends Packet {
 
     public static final String ELEMENT = "presence";
 
@@ -207,7 +207,6 @@ public class Presence extends XmlLangStanza {
     public XmlStringBuilder toXML() {
         XmlStringBuilder buf = new XmlStringBuilder();
         buf.halfOpenElement(ELEMENT);
-        buf.xmllangAttribute(language);
         addCommonAttributes(buf);
         if (type != Type.available) {
             buf.attribute("type", type);

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

@@ -1,45 +0,0 @@
-/**
- *
- * Copyright © 2014 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.packet;
-
-
-/**
- * Abstract class for stanzas that can contain a 'xml:lang' definition in their
- * top level element, ie. Message and Presence stanzas.
- */
-public abstract class XmlLangStanza extends Packet {
-    protected String language;
-
-    /**
-     * Returns the xml:lang of this Stanza, or null if one has not been set.
-     *
-     * @return the xml:lang of this Stanza, or null.
-     */
-    public String getLanguage() {
-        return language;
-    }
-
-    /**
-     * Sets the xml:lang of this Stanza.
-     *
-     * @param language the xml:lang of this Stanza.
-     */
-    public void setLanguage(String language) {
-        this.language = language;
-    }
-
-}