private void registerTaskEvents() {
   TaskCompletedHandler eventResponseHandler = new TaskCompletedHandler();
   TaskEventKey key = new TaskEventKey(TaskCompletedEvent.class, -1);
   client.registerForEvent(key, false, eventResponseHandler);
   key = new TaskEventKey(TaskFailedEvent.class, -1);
   client.registerForEvent(key, false, eventResponseHandler);
   key = new TaskEventKey(TaskSkippedEvent.class, -1);
   client.registerForEvent(key, false, eventResponseHandler);
 }