message: api no longer allows null accept function object
diff: @@ -173,7 +173,7 @@ void test_listen_duplicate_port(int port)
  {
  tcp_socket sever_sock_first( the_kernel.get() );
  - sever_sock_first.listen("", std::to_string(port), {}).wait();
  + sever_sock_first.listen("", std::to_string(port), [](std::unique_ptr<tcp_socket>&,uverr){}).wait();
  if (!sever_sock_first.is_listening())
  {
  cout << "unable to get port" << endl;
  