fun receiveData(
    source: BufferedSource,
    length: Int,
  ) {
    lock.assertNotHeld()

    this.source.receive(source, length.toLong())
  }

  /** Accept headers from the network and store them until the client calls [takeHeaders]. */
  fun receiveHeaders(
    headers: Headers,
    inFinished: Boolean,
  ) {
    lock.assertNotHeld()

    val open: Boolean
    this.withLock {