问在Play + Scala中构建websockets时出现“无法解决重载方法actorRef”错误

EN

package controllers

import play.api.mvc._

import javax.inject._
import akka.actor._
import akka.stream.Materializer
import play.libs.streams.ActorFlow


@Singleton
class HomeController @Inject()(cc: ControllerComponents)(implicit system: ActorSystem, mat: Materializer) extends AbstractController(cc) {

  def ws = WebSocket.accept[String, String] { request =>
    ActorFlow.actorRef { out =>
      MyWebSocketActor.props(out)
    }
  }
}

object MyWebSocketActor {
  def props(out: ActorRef) = Props(new MyWebSocketActor(out))
}

class MyWebSocketActor(out: ActorRef) extends Actor {
  def receive = {
    case msg: String =>
      out ! ("I received your message: " + msg)
  }
}