*     not yet been sent.
   */
  fun getSink(): Sink {
    this.withLock {
      check(hasResponseHeaders || isLocallyInitiated) {
        "reply before requesting the sink"
      }
    }
    return sink
  }

  /**
   * Abnormally terminate this stream. This blocks until the `RST_STREAM` frame has been
   * transmitted.
   */
  @Throws(IOException::class)