code: @Override
      public void handleEvent(Object event) throws GuacamoleException {
          for (final Listener listener : listeners) {
              listener.handleEvent(event);
          }
      }
docs: Notifies registered listeners than an event has occurred. Notification continues
  until a given listener throws a GuacamoleException or other runtime exception, or
  until all listeners have been notified.
  
  @param event
  An object that describes the event that has occurred.
  
  @throws GuacamoleException
  If a registered listener throws a GuacamoleException.