Combining multiple unmarshallers for different dataformats for one path

MultipleUnmarshallers.scala

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model.ContentTypes
import akka.http.scaladsl.unmarshalling.{FromEntityUnmarshaller, Unmarshaller}
import akka.stream.ActorMaterializer

object MultipleUnmarshallers extends App {

  implicit val system = ActorSystem()
  implicit val materializer = ActorMaterializer()
  import system.dispatcher

  case class Thing(n: Int)

  import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport._
  import spray.json.DefaultJsonProtocol._

  val jsonUnmarshaller: FromEntityUnmarshaller[Thing] = jsonFormat1(Thing)
  val textUnmarshaller: FromEntityUnmarshaller[Thing] =
    Unmarshaller.stringUnmarshaller.map(str => Thing(str.toInt))
      .forContentTypes(ContentTypes.`text/plain(UTF-8)`)


  implicit val combined: FromEntityUnmarshaller[Thing] =
    Unmarshaller.firstOf(jsonUnmarshaller, textUnmarshaller)

  import akka.http.scaladsl.server.Directives._

  val route =
    post {
      entity(as[Thing]) { thing =>
        complete("Ok" + thing)
      }
    }

  Http().bindAndHandle(route, "127.0.0.1", 8080).onComplete(println)
}