Merge branch '4.1'

Conflicts:
	smack-core/src/main/java/org/jivesoftware/smack/StanzaListener.java
	smack-core/src/main/java/org/jivesoftware/smack/XMPPConnection.java
	smack-core/src/main/java/org/jivesoftware/smack/packet/Stanza.java
	smack-core/src/main/java/org/jivesoftware/smack/util/PacketParserUtils.java
	version.gradle

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/NodeInformationProvider.java

@@ -64,9 +64,9 @@ public interface NodeInformationProvider {
     List<DiscoverInfo.Identity> getNodeIdentities();
 
     /**
-     * Returns a list of the packet extensions defined in the node.
+     * Returns a list of the stanza(/packet) extensions defined in the node.
      *
-     * @return a list of the packet extensions defined in the node.
+     * @return a list of the stanza(/packet) extensions defined in the node.
      */
     List<ExtensionElement> getNodePacketExtensions();
 }

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/ServiceDiscoveryManager.java

@@ -29,6 +29,7 @@ import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.Stanza;
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.XMPPError;
+import org.jivesoftware.smack.util.Objects;
 import org.jivesoftware.smackx.caps.EntityCapsManager;
 import org.jivesoftware.smackx.disco.packet.DiscoverInfo;
 import org.jivesoftware.smackx.disco.packet.DiscoverItems;
@@ -202,9 +203,10 @@ public class ServiceDiscoveryManager extends Manager {
      *
      * @param identity
      */
-    public void setIdentity(Identity identity) {
-        if (identity == null) throw new IllegalArgumentException("Identity can not be null");
-        this.identity = identity;
+    public synchronized void setIdentity(Identity identity) {
+        this.identity = Objects.requireNonNull(identity, "Identity can not be null");
+        // Notify others of a state change of SDM. In order to keep the state consistent, this
+        // method is synchronized
         renewEntityCapsVersion();
     }
 
@@ -234,8 +236,10 @@ public class ServiceDiscoveryManager extends Manager {
      * 
      * @param identity
      */
-    public void addIdentity(DiscoverInfo.Identity identity) {
+    public synchronized void addIdentity(DiscoverInfo.Identity identity) {
         identities.add(identity);
+        // Notify others of a state change of SDM. In order to keep the state consistent, this
+        // method is synchronized
         renewEntityCapsVersion();
     }
 
@@ -246,9 +250,11 @@ public class ServiceDiscoveryManager extends Manager {
      * @param identity
      * @return true, if successful. Otherwise the default identity was given.
      */
-    public boolean removeIdentity(DiscoverInfo.Identity identity) {
+    public synchronized boolean removeIdentity(DiscoverInfo.Identity identity) {
         if (identity.equals(this.identity)) return false;
         identities.remove(identity);
+        // Notify others of a state change of SDM. In order to keep the state consistent, this
+        // method is synchronized
         renewEntityCapsVersion();
         return true;
     }
@@ -288,17 +294,15 @@ public class ServiceDiscoveryManager extends Manager {
      *
      * @param response the discover info response packet
      */
-    public void addDiscoverInfoTo(DiscoverInfo response) {
+    public synchronized void addDiscoverInfoTo(DiscoverInfo response) {
         // First add the identities of the connection
         response.addIdentities(getIdentities());
 
         // Add the registered features to the response
-        synchronized (features) {
-            for (String feature : getFeatures()) {
-                response.addFeature(feature);
-            }
-            response.addExtension(extendedInfo);
+        for (String feature : getFeatures()) {
+            response.addFeature(feature);
         }
+        response.addExtension(extendedInfo);
     }
 
     /**
@@ -358,45 +362,41 @@ public class ServiceDiscoveryManager extends Manager {
      * 
      * @return a List of the supported features by this XMPP entity.
      */
-    public List<String> getFeatures() {
-        synchronized (features) {
-            return new ArrayList<String>(features);
-        }
+    public synchronized List<String> getFeatures() {
+        return new ArrayList<String>(features);
     }
 
     /**
      * Registers that a new feature is supported by this XMPP entity. When this client is 
      * queried for its information the registered features will be answered.<p>
      *
-     * Since no packet is actually sent to the server it is safe to perform this operation
+     * Since no stanza(/packet) is actually sent to the server it is safe to perform this operation
      * before logging to the server. In fact, you may want to configure the supported features
      * before logging to the server so that the information is already available if it is required
      * upon login.
      *
      * @param feature the feature to register as supported.
      */
-    public void addFeature(String feature) {
-        synchronized (features) {
-            if (!features.contains(feature)) {
-                features.add(feature);
-                renewEntityCapsVersion();
-            }
-        }
+    public synchronized void addFeature(String feature) {
+        features.add(feature);
+        // Notify others of a state change of SDM. In order to keep the state consistent, this
+        // method is synchronized
+        renewEntityCapsVersion();
     }
 
     /**
      * Removes the specified feature from the supported features by this XMPP entity.<p>
      *
-     * Since no packet is actually sent to the server it is safe to perform this operation
+     * Since no stanza(/packet) is actually sent to the server it is safe to perform this operation
      * before logging to the server.
      *
      * @param feature the feature to remove from the supported features.
      */
-    public void removeFeature(String feature) {
-        synchronized (features) {
-            features.remove(feature);
-            renewEntityCapsVersion();
-        }
+    public synchronized void removeFeature(String feature) {
+        features.remove(feature);
+        // Notify others of a state change of SDM. In order to keep the state consistent, this
+        // method is synchronized
+        renewEntityCapsVersion();
     }
 
     /**
@@ -405,10 +405,8 @@ public class ServiceDiscoveryManager extends Manager {
      * @param feature the feature to look for.
      * @return a boolean indicating if the specified featured is registered or not.
      */
-    public boolean includesFeature(String feature) {
-        synchronized (features) {
-            return features.contains(feature);
-        }
+    public synchronized boolean includesFeature(String feature) {
+        return features.contains(feature);
     }
 
     /**
@@ -417,7 +415,7 @@ public class ServiceDiscoveryManager extends Manager {
      * specified by XEP-0128.
      * <p>
      *
-     * Since no packet is actually sent to the server it is safe to perform this
+     * Since no stanza(/packet) is actually sent to the server it is safe to perform this
      * operation before logging to the server. In fact, you may want to
      * configure the extended info before logging to the server so that the
      * information is already available if it is required upon login.
@@ -426,8 +424,10 @@ public class ServiceDiscoveryManager extends Manager {
      *            the data form that contains the extend service discovery
      *            information.
      */
-    public void setExtendedInfo(DataForm info) {
+    public synchronized void setExtendedInfo(DataForm info) {
       extendedInfo = info;
+      // Notify others of a state change of SDM. In order to keep the state consistent, this
+      // method is synchronized
       renewEntityCapsVersion();
     }
 
@@ -460,11 +460,13 @@ public class ServiceDiscoveryManager extends Manager {
      * Removes the data form containing extended service discovery information
      * from the information returned by this XMPP entity.<p>
      *
-     * Since no packet is actually sent to the server it is safe to perform this
+     * Since no stanza(/packet) is actually sent to the server it is safe to perform this
      * operation before logging to the server.
      */
-    public void removeExtendedInfo() {
+    public synchronized void removeExtendedInfo() {
        extendedInfo = null;
+       // Notify others of a state change of SDM. In order to keep the state consistent, this
+       // method is synchronized
        renewEntityCapsVersion();
     }
 
@@ -599,7 +601,7 @@ public class ServiceDiscoveryManager extends Manager {
       * be returned by the server whenever the server receives a disco request targeted to the bare
       * address of the client (i.e. user@host.com).
       * 
-      * @param info the discover info packet to check.
+      * @param info the discover info stanza(/packet) to check.
       * @return true if the server supports publishing of items.
       */
      public static boolean canPublishItems(DiscoverInfo info) {