Status.Success doesn't complete the stream

akk-stream-actor-integration-bug?.scala

package sample.stream

import akka.actor.ActorSystem
import akka.stream.{ OverflowStrategy, ActorMaterializer }
import akka.stream.scaladsl._
import akka.actor.Status

import scala.util.{ Failure, Success }

object BasicTransformation {

  def main(args: Array[String]): Unit = {
    implicit val system = ActorSystem("Sys")
    import system.dispatcher

    implicit val materializer = ActorMaterializer()

    val (actor, future) = Source.actorRef[Int](1024, OverflowStrategy.fail)
      .toMat(Sink.fold[Int, Int](0)(_ + _))(Keep.both)
      .run()

    future onComplete {
      case Success(res) =>
        println(s"result is $res")
        system.terminate()
      case Failure(e) =>
        println(s"Failure: $e")
        system.terminate()
    }

    actor ! 1
    actor ! 2
    actor ! Status.Success  //it doesn't complete the stream and is treated like a normal element, something wrong?
  }
}