) {
    this.withLock {
      if (closed) throw IOException("closed")
      hpackWriter.writeHeaders(requestHeaders)

      val byteCount = hpackBuffer.size
      val length = minOf(maxFrameSize - 4L, byteCount).toInt()
      frameHeader(
        streamId = streamId,
        length = length + 4,
        type = TYPE_PUSH_PROMISE,
        flags = if (byteCount == length.toLong()) FLAG_END_HEADERS else 0,
      )