docs: public static BiFunction<WebsocketInbound, WebsocketOutbound, Publisher<Void>> newHandler(
        ConnectionAcceptor acceptor, int mtu) {
      return (in, out) -> {
        DuplexConnection connection = new WebsocketDuplexConnection((Connection) in);
        if (mtu > 0) {
          connection =
              new FragmentationDuplexConnection(
                  connection, ByteBufAllocator.DEFAULT, mtu, false, "server");
        }
        return acceptor.apply(connection).then(out.neverComplete());
      };
    }