code: public Future<Void> start(final int port) {
          final ChannelFuture channelFuture = this.bootstrap.bind(port);
          this.allChannels.add(channelFuture.channel());
  
          return channelFuture;
      }
docs: Starts this mock server and listens for traffic on the given port.
  
  @param port the port to which this server should bind
  
  @return a {@code Future} that will succeed when the server has bound to the given port and is ready to accept
  traffic