ActorSystem): PartialFunction[HttpRequest, scala.concurrent.Future[HttpResponse]] = {
  implicit val ec: ExecutionContext = mat.executionContext
  import GreeterService.Serializers._

  def handle(request: HttpRequest, method: String): scala.concurrent.Future[HttpResponse] = method match {
    case &quot;SayHello&quot; =&gt;
      val responseCodec = Codecs.negotiate(request)
      val metadata = new MetadataImpl(request.headers)
      GrpcMarshalling.unmarshal(request)(HelloRequestSerializer, mat)
        