How to generate swagger document for akka http web socket route?

Question

How to generate swagger document for akka http web socket route ?

I have able to write akka Http get,put,post,delete. for example

 @Path("/postPing")
 @ApiOperation(value = "Find a ping", notes = "Returns a pong",
 httpMethod = "POST",response = classOf[String])
 @ApiImplicitParams(Array(
 new ApiImplicitParam(name = "data", value = "\"data\" to sum",     required = true,
  dataType = "string", paramType = "query"),
new ApiImplicitParam(name = "file", required = true,
  dataType = "file", paramType = "query")
))
@ApiResponses(Array(
new ApiResponse(code = 404, message = "websocket not found"),
new ApiResponse(code = 200, message = "websocket found"),
new ApiResponse(code = 400, message = "Invalid websocket supplied")))
def postRoute = path("postPing") {
complete("post pong")
}

But I need for Akka web socket

def webSocketRoute: Route = path("websocket") {
handleWebSocketMessages(broadcast)
}
def broadcast: Flow[Message, Message, Any] = {
Flow[Message].mapConcat {
  case tm: TextMessage =>
    TextMessage(tm.textStream) :: Nil
 }
 }

For example To connect with websocket server

/connect ws://echo.websocket.org/websocket

To send data to websocket server

/send Hello\ world

Thanks in Advance