OF-573: Fix BOSH delivery timing/synchronization issue

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/trunk@13373 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/openfire/http/HttpSession.java

@@ -807,9 +807,11 @@ public class HttpSession extends LocalClientSession {
         // We aren't supposed to hold connections open or we already have some packets waiting
         // to be sent to the client.
         if (isPollingSession() || (pendingElements.size() > 0 && connection.getRequestId() == lastRequestID + 1)) {
+        	synchronized(pendingElements) {
 	            deliver(connection, pendingElements);
 	            lastRequestID = connection.getRequestId();
 	            pendingElements.clear();
+        	}
             connectionQueue.add(connection);
             Collections.sort(connectionQueue, connectionComparator);
         }