PipeThroughInputStreamTest.scala

  def pipeThroughInputStream(pipeThrough: InputStream => InputStream)(implicit mat: Materializer): Flow[ByteString, ByteString, NotUsed] = {
    Flow.lazyFlow { () =>
      val sink = StreamConverters.asInputStream(5.minutes)
      val (is, matSink) = sink.preMaterialize()
      val source = StreamConverters.fromInputStream(() => pipeThrough(is))
      Flow.fromSinkAndSource(matSink, source)
    }.mapMaterializedValue(f =>
      f.onComplete {
        case Failure(exception) => logger.error("error", exception)
        case Success(value) =>
      }
      akka.NotUsed
    )
  }