code: public void shutDown() {
      logger.info("Shutting down RPC server.");
      channel.close().addListener(new GenericFutureListener<Future<Void>>() {
  
        @Override
        public void operationComplete(Future<Void> future) throws Exception {
          parentGroup.shutdownGracefully();
          childGroup.shutdownGracefully();
        }
      }).awaitUninterruptibly();
    }
docs: Stops this server.
  <p/>
  <p>This is a synchronous operation.</p>