Add copy constructor to Message and Presence

and also implement Cloneable and add clone() methods.

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

@@ -50,7 +50,7 @@ import org.jivesoftware.smack.util.XmlStringBuilder;
  *
  * @author Matt Tucker
  */
-public final class Message extends Stanza {
+public final class Message extends Stanza implements Cloneable {
 
     public static final String ELEMENT = "message";
     public static final String BODY = "body";
@@ -98,6 +98,23 @@ public final class Message extends Stanza {
         setBody(body);
     }
 
+    /**
+     * Copy constructor.
+     * <p>
+     * This does not perform a deep clone, as extension elements are shared between the new and old
+     * instance.
+     * </p>
+     *
+     * @param other
+     */
+    public Message(Message other) {
+        super(other);
+        this.type = other.type;
+        this.thread = other.thread;
+        this.subjects.addAll(other.subjects);
+        this.bodies.addAll(other.bodies);
+    }
+
     /**
      * Returns the type of the message. If no type has been set this method will return {@link
      * org.jivesoftware.smack.packet.Message.Type#normal}.
@@ -445,6 +462,19 @@ public final class Message extends Stanza {
         return buf;
     }
 
+    /**
+     * Creates and returns a copy of this message stanza.
+     * <p>
+     * This does not perform a deep clone, as extension elements are shared between the new and old
+     * instance.
+     * </p>
+     * @return a clone of this message.
+     */
+    @Override
+    public Message clone() {
+        return new Message(this);
+    }
+
     /**
      * Represents a message subject, its language and the content of the subject.
      */

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

@@ -55,7 +55,7 @@ import org.jivesoftware.smack.util.XmlStringBuilder;
  *
  * @author Matt Tucker
  */
-public final class Presence extends Stanza {
+public final class Presence extends Stanza implements Cloneable {
 
     public static final String ELEMENT = "presence";
 
@@ -88,6 +88,23 @@ public final class Presence extends Stanza {
         setMode(mode);
     }
 
+    /**
+     * Copy constructor.
+     * <p>
+     * This does not perform a deep clone, as extension elements are shared between the new and old
+     * instance.
+     * </p>
+     *
+     * @param other
+     */
+    public Presence(Presence other) {
+        super(other);
+        this.type = other.type;
+        this.status = other.status;
+        this.priority = other.priority;
+        this.mode = other.mode;
+    }
+
     /**
      * Returns true if the {@link Type presence type} is available (online) and
      * false if the user is unavailable (offline), or if this is a presence packet
@@ -228,6 +245,19 @@ public final class Presence extends Stanza {
         return buf;
     }
 
+    /**
+     * Creates and returns a copy of this presence stanza.
+     * <p>
+     * This does not perform a deep clone, as extension elements are shared between the new and old
+     * instance.
+     * </p>
+     * @return a clone of this presence.
+     */
+    @Override
+    public Presence clone() {
+        return new Presence(this);
+    }
+
     /**
      * An enum to represent the presence type. Note that presence type is often confused
      * with presence mode. Generally, if a user is signed in to a server, they have a presence