public static void MapMqtt(this ConnectionsRouteBuilder connection, PathString path)
 {
     connection.MapConnectionHandler <MqttConnectionHandler>(path, options =>
     {
         options.WebSockets.SubProtocolSelector = MqttSubProtocolSelector.SelectSubProtocol;
     });
 }
 /// <summary>
 /// Initializes a new instance of the <see cref="HubRouteBuilder"/> class.
 /// </summary>
 /// <param name="routes">The routes builder.</param>
 public HubRouteBuilder(ConnectionsRouteBuilder routes)
 {
     _routes = routes;
 }