class AsyncRequestBody : RequestBody() {
  private val requestBodySinks: BlockingQueue<BufferedSink> = LinkedBlockingQueue()

  override fun contentType(): MediaType? = null

  override fun writeTo(sink: BufferedSink) {
    requestBodySinks.add(sink)
  }

  override fun isDuplex(): Boolean = true

  @Throws(InterruptedException::class)
  fun takeSink(): BufferedSink {