): Sink {
    this.isDuplex = duplex
    val contentLength = request.body!!.contentLength()
    eventListener.requestBodyStart(call)
    val rawRequestBody = codec.createRequestBody(request, contentLength)
    return RequestBodySink(rawRequestBody, contentLength)
  }

  @Throws(IOException::class)
  fun flushRequest() {
    try {
      codec.flushRequest()
    } catch (e: IOException) {
      eventListener.requestFailed(call, e)