docs: @Handler
      public void onOpenConnection(OpenTcpConnection event) {
          try {
              SocketChannel socketChannel = SocketChannel.open(event.address());
              channels.add(new TcpChannelImpl(socketChannel));
          } catch (ConnectException e) {
              fire(new ConnectError(event, "Connection refused.", e));
          } catch (IOException e) {
              fire(new ConnectError(event, "Failed to open TCP connection.", e));
          }
      }