code: public static void deregisterMessagingEngineListener(
              final SibRaMessagingEngineListener listener, final String busName) {
  
          final String methodName = "deregisterMessagingEngineListener";
          if (TRACE.isEntryEnabled()) {
              SibTr.entry(TRACE, methodName, new Object[] { listener, busName });
          }
  
          synchronized (MESSAGING_ENGINE_LISTENERS) {
  
              final Set listeners = (Set) MESSAGING_ENGINE_LISTENERS.get(busName);
              if (listeners != null) {
                  listeners.remove(listener);
                  if (listeners.isEmpty()) {
                      MESSAGING_ENGINE_LISTENERS.remove(busName);
                  }
              }
  
          }
  
          if (TRACE.isEntryEnabled()) {
              SibTr.exit(TRACE, methodName);
          }
  
      }
docs: Deregisters a listener for active messaging engines on a bus.
  
  @param listener
  the listener to deregister
  @param busName
  the name of the bus the listener was registered with