* [requestBody] may return data after this call; that is the buffered data received before this
   * stream was canceled.
   *
   * This does nothing if [requestBody] and [responseBody] are already closed.
   *
   * For HTTP/2 this sends the [CANCEL](https://datatracker.ietf.org/doc/html/rfc7540#section-7)
   * error code.
   */
  fun cancel()

  }

  @Test fun cancelAllWhenEmptyDoesNotStartWorkerThread() {
    redQueue.execute("red task", 100.µs) {
      error("expected to be canceled")
    }
    assertThat(taskFaker.executeCallCount).isEqualTo(1)

    blueQueue.execute("task", 100.µs) {
      error("expected to be canceled")
    }
    assertThat(taskFaker.executeCallCount).isEqualTo(1)

    redQueue.cancelAll()

that by default Kotlin's Dispatchers are not used.

Cancellation if implemented sensibly in both directions.
Cancelling a coroutine scope, will cancel the call.
Cancelling a call, will throw a CancellationException

  /** Returns the trailers after the HTTP response. May be empty. */
  @Throws(IOException::class)
  fun trailers(): Headers

  /**
   * Cancel this stream. Resources held by this stream will be cleaned up, though not synchronously.
   * That may happen later by the connection pool thread.
   */
  fun cancel()

  /**
   * Carries an exchange. This is usually a connection, but it could also be a connect plan for

  override fun connectTcp() = error("already connected")

  override fun connectTlsEtc() = error("already connected")

  override fun handleSuccess() = connection

  override fun cancel() = error("unexpected cancel")

  override fun retry() = error("unexpected retry")

    // Play it back.
    connect(peer, PushObserver.CANCEL, Http2Connection.Listener.REFUSE_INCOMING_STREAMS)

    // Verify the peer received what was expected.
    val rstStream = peer.takeFrame()
    assertThat(rstStream.type).isEqualTo(Http2.TYPE_RST_STREAM)
    assertThat(rstStream.streamId).isEqualTo(2)
    assertThat(rstStream.errorCode).isEqualTo(ErrorCode.CANCEL)
  }

  /**

  fun noNewExchangesOnConnection() {
    codec.carrier.noNewExchanges()
  }

  fun cancel() {
    codec.cancel()
  }

  /**
   * Revoke this exchange's access to streams. This is necessary when a follow-up request is
   * required but the preceding exchange hasn't completed yet.
   */
  fun detachWithViolence() {
    codec.cancel()
    call.messageDone(this, requestDone = true, responseDone = true, e = null)
  }

	public fun cacheMiss (Lokhttp3/Call;)V
	public fun callEnd (Lokhttp3/Call;)V
	public fun callFailed (Lokhttp3/Call;Ljava/io/IOException;)V
	public fun callStart (Lokhttp3/Call;)V
	public fun canceled (Lokhttp3/Call;)V
	public fun connectEnd (Lokhttp3/Call;Ljava/net/InetSocketAddress;Ljava/net/Proxy;Lokhttp3/Protocol;)V

    override val call: Call,
    val ioe: IOException,
  ) : CallEvent() {
    override fun closes(event: CallEvent): Boolean = event is CallStart && call == event.call
  }

  data class Canceled(
    override val timestampNs: Long,
    override val call: Call,
  ) : CallEvent()

  data class RequestHeadersStart(
    override val timestampNs: Long,
    override val call: Call,
  ) : CallEvent()

E0002..E001F  ; disallowed                             # NA   <reserved-E0002>..<reserved-E001F>
E0020..E007F  ; disallowed                             # 3.1  TAG SPACE..CANCEL TAG
E0080..E00FF  ; disallowed                             # NA   <reserved-E0080>..<reserved-E00FF>
E0100..E01EF  ; ignored                                # 4.0  VARIATION SELECTOR-17..VARIATION SELECTOR-256