/** Indicates the reason why this stream was canceled. */
  fun onReset(
    streamId: Int,
    errorCode: ErrorCode,
  )

  companion object {
    @JvmField val CANCEL: PushObserver = PushObserverCancel()

    private class PushObserverCancel : PushObserver {
      override fun onRequest(
        streamId: Int,
        requestHeaders: List<Header>,
      ): Boolean = true

      override fun onHeaders(
        streamId: Int,