code: public void removeEventSourceListener(EventSourceListener listener) {
          LOG.entering(CLASS_NAME, "removeEventSourceListener", listener);
          if (listener == null) {
              throw new NullPointerException("listener");
          }
          listeners.remove(listener);
      }
docs: Removes the given EventSource listener from the listener list.
  
  @param listener
  EventSourceListener to be unregistered