trackFailure(e)
      throw e
    }
  }

  @Throws(IOException::class)
  fun createRequestBody(
    request: Request,
    duplex: Boolean,
  ): Sink {
    this.isDuplex = duplex
    val contentLength = request.body!!.contentLength()
    call.eventListener.requestBodyStart(call)
    val rawRequestBody = codec.createRequestBody(request, contentLength)
    return RequestBodySink(
      delegate = rawRequestBody,

   * return the value but instead throw an exception.
   */
  private var trailers: Headers? = null

  override val isResponseComplete: Boolean
    get() = state == STATE_CLOSED

  override fun createRequestBody(
    request: Request,
    contentLength: Long,
  ): Sink =
    when {
      request.body?.isDuplex() == true -> {
        throw ProtocolException(
          "Duplex connections are not supported for HTTP/1",