}
    check(state == STATE_READING_RESPONSE_BODY || state == STATE_CLOSED) {
      "Trailers cannot be read because the state is $state"
    }
    return trailers
  }

  override fun flushRequest() {
    socket.sink.flush()
  }

  override fun finishRequest() {
    socket.sink.flush()
  }

  /** Returns bytes of a request header for sending on an HTTP transport. */
  fun writeRequest(