code: @Override
      public void sendAckExpectedMessage(
                                         long ackExpStamp,
                                         int priority,
                                         Reliability reliability,
                                         SIBUuid12 stream)
                      throws SIResourceException
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(tc, "sendAckExpectedMessage",
                          new Object[] { new Long(ackExpStamp), new Integer(priority), reliability, stream });
          HashMap allPubSubOutputHandlers = _destination.getAllPubSubOutputHandlers();
          try
          {
              Iterator itr = allPubSubOutputHandlers.values().iterator();
  
              while (itr.hasNext())
              {
                  PubSubOutputHandler handler = (PubSubOutputHandler) itr.next();
  
                  // Send AckExpected to all OutputHandlers
                  handler.processAckExpected(ackExpStamp, priority, reliability, stream);
              }
          } finally
          {
              // By calling the getAllPubSubOutputHandlers it will lock the 
              // handlers
              _destination.unlockPubsubOutputHandlers();
          }
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(tc, "sendAckExpectedMessage");
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.ws.sib.processor.impl.interfaces.DownstreamControl#sendAckExpectedMessage(long, com.ibm.ws.sib.trm.topology.Cellule, int, com.ibm.ws.sib.common.Reliability)