code: @Override
      public final void messageSent(NextFilter nextFilter, IoSession session,
              WriteRequest writeRequest) {
          if (eventTypes.contains(IoEventType.MESSAGE_SENT)) {
              IoFilterEvent event = new IoFilterEvent(nextFilter, IoEventType.MESSAGE_SENT,
                  session, writeRequest); 
              fireEvent(event);
          } else {
              nextFilter.messageSent(session, writeRequest);
          }
      }
docs: {@inheritDoc}