code: public final UdpClient doOnDisconnected(Consumer<? super Connection> doOnDisconnected) {
  		Objects.requireNonNull(doOnDisconnected, "doOnDisconnected");
  		return new UdpClientDoOn(this, null, null, doOnDisconnected);
  	}
docs: Setup a callback called when {@link io.netty.channel.Channel} is
  disconnected.
  
  @param doOnDisconnected a consumer observing client stop event
  
  @return a new {@link UdpClient}