* 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

 *
 * 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() {

    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 =

  }

  private fun newEmptyKeyStore(keyStoreType: String?): KeyStore {
    return KeyStore.getInstance(keyStoreType ?: KeyStore.getDefaultType()).apply {
      val inputStream: InputStream? = null // By convention, 'null' creates an empty key store.
      load(inputStream, password)
    }
  }

   * messages. This does nothing if the web socket has already been closed or canceled.
   */
  fun cancel()

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