object : EventListener() {
        var socket: SSLSocket? = null
        var closed = false

        override fun connectionAcquired(
          call: Call,
          connection: Connection,
        ) {
          socket = connection.socket() as SSLSocket
        }

        override fun requestHeadersStart(call: Call) {
          if (closed) {
            throw IOException("fake socket failure")
          }
        }

    if (eventSequence.isEmpty()) {
      assertThat(e).isInstanceOf(ConnectionEvent.ConnectStart::class.java)
    } else {
      eventSequence.forEach loop@{
        when (e.closes(it)) {
          null -> return // no open event
          true -> return // found open event
          false -> return@loop // this is not the open event so continue
        }
      }

    return writer
  }

  /**
   * Shortens the last frame from its original length to `length`. This will cause the peer to
   * close the socket as soon as this frame has been written; otherwise the peer stays open until
   * explicitly closed.
   */
  fun truncateLastFrame(length: Int): Http2Writer {
    val lastFrame = outFrames.removeAt(outFrames.size - 1)
    require(length < bytesOut.size - lastFrame.start)

  fun request(): Request

  /**
   * Immediately and violently release resources held by this event source. This does nothing if
   * 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

  /**
   * Called when the HTTP response was successfully returned by the remote server. The callback may
   * proceed to read the response body with [Response.body]. The response is still live until its
   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not

    /**
     * How many concurrent calls should be possible to make at any time.
     * The pool will routinely try to pre-emptively open connections to satisfy this minimum.
     * Connections will still be closed if they idle beyond the keep-alive but will be replaced.
     */
    @JvmField val minimumConcurrentCalls: Int = 0,
    /** How long to wait to retry pre-emptive connection attempts that fail. */

    val relay = edit(file, upstream, metadata, 1024)
    val source1 = relay.newSource()
    val source2 = relay.newSource()
    source1!!.close()
    source1.close() // Unnecessary. Shouldn't decrement the reference count.
    assertThat(relay.isClosed).isFalse()
    source2!!.close()
    assertThat(relay.isClosed).isTrue()
    assertFile(Relay.PREFIX_DIRTY, -1L, -1, null, null)
  }

  @Test
  fun racingReaders() {

 * **Exchange** carries a single HTTP request/response pair.

 * **ExchangeFinder** chooses which connection carries each exchange. Where possible it will use the same connection for all exchanges in a single call. It prefers reusing pooled connections over establishing new connections.      

#### Per-Connection Locks

 *
 * All event methods must execute fast, without external locking, cannot throw exceptions,
 * attempt to mutate the event parameters, or be reentrant back into the client.
 * Any IO - writing to files or network should be done asynchronously.
 */
@ExperimentalOkHttpApi
abstract class ConnectionListener {
  /**
   * Invoked as soon as a call causes a connection to be started.
   */

`checkstyle-result.xml` file.

Some general advice

- Don’t change public API lightly, avoid if possible, and include your reasoning in the PR if essential.  It causes pain for developers who use OkHttp and sometimes runtime errors.
- Favour a working external library if appropriate.  There are many examples of OkHttp libraries that can sit on top or hook in via existing APIs.