Invoke PacketCollectors in ListenerNotification

Also make executorService a non-ScheduledExecutorService. This was an
artifact from times where executorService as used to schedule
Runnables. But now it's just used to queue the receive packets in
Runnables and call the packet collectors and listeners.

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

@@ -25,11 +25,13 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.locks.Lock;
@@ -204,8 +206,8 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
      * important that we use a <b>single threaded ExecutorService</b> in order to guarantee that the
      * PacketListeners are invoked in the same order the stanzas arrived.
      */
-    private final ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1,
-                    new SmackExecutorThreadFactory(connectionCounterValue));
+    private final ThreadPoolExecutor executorService = new ThreadPoolExecutor(1, 1, 0, TimeUnit.SECONDS,
+                    new ArrayBlockingQueue<Runnable>(100), new SmackExecutorThreadFactory(connectionCounterValue));
 
     /**
      * SmackExecutorThreadFactory is a *static* inner class of XMPPConnection. Note that we must not
@@ -840,12 +842,6 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
      * @param packet the packet to process.
      */
     protected void processPacket(Packet packet) {
-        if (packet == null) {
-            return;
-        }
-
-        invokePacketCollectors(packet);
-
         // Deliver the incoming packet to listeners.
         executorService.submit(new ListenerNotification(packet));
     }
@@ -873,7 +869,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
     }
 
     /**
-     * A runnable to notify all listeners of a packet.
+     * A runnable to notify all listeners and packet collectors of a packet.
      */
     private class ListenerNotification implements Runnable {
 
@@ -884,6 +880,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         }
 
         public void run() {
+            invokePacketCollectors(packet);
             notifiyReceivedListeners(packet);
         }
     }