* the event source has already been closed or canceled.
   */
  fun cancel()

  fun interface Factory {
    /**
     * Creates a new event source and immediately returns it. Creating an event source initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be

    @JvmField val PREFIX_CLEAN = "OkHttp cache v1\n".encodeUtf8()

    @JvmField val PREFIX_DIRTY = "OkHttp DIRTY :(\n".encodeUtf8()
    private const val FILE_HEADER_SIZE = 32L

    /**
     * Creates a new relay that reads a live stream from [upstream], using [file] to share that data
     * with other sources.
     *
     * **Warning:** callers to this method must immediately call [newSource] to create a source and

 *
 * To make HTTPS calls using an HTTP proxy server OkHttp must first negotiate a connection with
 * the proxy. This proxy connection is called a "TLS Tunnel" and is specified by
 * [RFC 2817][1]. The HTTP CONNECT request that creates this tunnel connection is special: it
 * does not participate in any [interceptors][Interceptor] or [event listeners][EventListener]. It
 * doesn't include the motivating request's HTTP headers or even its full URL; only the target

This [sample factory](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEvents.java) creates a unique ID for each call and uses that ID to differentiate calls in log messages.

```java
class PrintingEventListener extends EventListener {
  public static final Factory FACTORY = new Factory() {

    state = STATE_READING_RESPONSE_BODY
    carrier.noNewExchanges()
    return UnknownLengthSource()
  }

  /**
   * Sets the delegate of `timeout` to [Timeout.NONE] and resets its underlying timeout
   * to the default configuration. Use this to avoid unexpected sharing of timeouts between pooled
   * connections.
   */
  private fun detachTimeout(timeout: ForwardingTimeout) {

    operator.write(80, buffer, buffer.size)
    assertThat(snapshot()).isEqualTo(
      (
        "" +
          "god creates dinosaurs. " +
          "god destroys dinosaurs. " +
          "god creates man. " +
          "man destroys god. " +
          "man creates dinosaurs. "
      ).encodeUtf8(),
    )
  }

  @Test
  fun multipleOperatorsShareOneFile() {
    val operatorA =

 *
 * This implementation assumes we do not send an increased [frame][Settings.getMaxFrameSize] to the
 * peer. Hence, we expect all frames to have a max length of [Http2.INITIAL_MAX_FRAME_SIZE].
 */
class Http2Reader(
  /** Creates a frame reader with max header table size of 4096. */
  private val source: BufferedSource,
  private val client: Boolean,
) : Closeable {
  private val continuation: ContinuationSource = ContinuationSource(this.source)

    `new Challenge(scheme, realm)` you must provide non-null values. These were
    never null in challenges created by OkHttp, but could have been null in
    application code that creates challenges.

 *  New: The `TlsVersion` of a `Handshake` is now non-null. If you are calling
    `Handshake.get()` with a null TLS version, you must instead now provide a

      routes = routes,
      attempt = 0,
      tunnelRequest = tunnelRequest,
      connectionSpecIndex = -1,
      isTlsFallback = false,
    )
  }

  /**
   * Returns a request that creates a TLS tunnel via an HTTP proxy. Everything in the tunnel request
   * is sent unencrypted to the proxy server, so tunnels include only the minimum set of headers.

 *  New: ConnectionSpec can now be configured to use the SSL socket's default
    cipher suites. To use, set the cipher suites to `null`.
 *  New: Support `DELETE` with a request body.
 *  New: `Headers.of(Map)` creates headers from a Map.


## Version 2.2.0

_2014-12-30_

 *  **`RequestBody.contentLength()` now throws `IOException`.**
    This is a source-incompatible change. If you have code that calls