printEvent("callStart");
  }

  @Override public void callEnd(Call call) {
    printEvent("callEnd");
  }

  ...
}
```

We can use this listener to race a pair of concurrent HTTP requests:

```java
Request washingtonPostRequest = new Request.Builder()
    .url("https://www.washingtonpost.com/")
    .build();
client.newCall(washingtonPostRequest).enqueue(new Callback() {

  @JvmOverloads
  constructor(
    val requiredPlatformName: String? = null,
    val platform: Platform? = null,
  ) : BeforeEachCallback, AfterEachCallback, InvocationInterceptor {
    private val versionChecks = mutableListOf<Pair<Matcher<out Any>, Matcher<out Any>>>()

    override fun beforeEach(context: ExtensionContext) {
      setupPlatform()
    }

    override fun afterEach(context: ExtensionContext) {
      resetPlatform()
    }

    // punctuation space
    assertThat(parse("http://h/\u2008").encodedPath).isEqualTo("/%E2%80%88")
    // thin space
    assertThat(parse("http://h/\u2009").encodedPath).isEqualTo("/%E2%80%89")
    // hair space
    assertThat(parse("http://h/\u200a").encodedPath).isEqualTo("/%E2%80%8A")
    // zero-width space
    assertThat(parse("http://h/\u200b").encodedPath).isEqualTo("/%E2%80%8B")
    // zero-width non-joiner

 *
 * All start/connect/acquire events will eventually receive a matching end/release event, either
 * successful (non-null parameters), or failed (non-null throwable). The first common parameters of
 * each event pair are used to link the event in case of concurrent or repeated events e.g.
 * `dnsStart(call, domainName)` → `dnsEnd(call, domainName, inetAddressList)`.
 *
 * Events are typically nested with this structure:
 *

   * request is transmitted. This is only interesting for duplex calls where the request and
   * response may be interleaved.
   *
   * Read this value only once for each enter/exit pair because its value can change.
   */
  private fun doReadTimeout() = !connection.client || sink.closed || sink.finished

  /**
   * A source that reads the incoming data frames of a stream. Although this class uses

  private lateinit var server: MockWebServer
  private lateinit var client: OkHttpClient

  val listener = RecordingEventListener()

  fun setUp(mode: Pair<CancelMode, ConnectionType>) {
    this.cancelMode = mode.first
    this.connectionType = mode.second

    if (connectionType == H2) {
      platform.assumeHttp2Support()
    }

  @ArgumentsSource(FileSystemParamProvider::class)
  fun emptyCache(parameters: Pair<FileSystem, Boolean>) {
    setUp(parameters.first, parameters.second)
    cache.close()
    assertJournalEquals()
  }

  @ParameterizedTest
  @ArgumentsSource(FileSystemParamProvider::class)
  fun recoverFromInitializationFailure(parameters: Pair<FileSystem, Boolean>) {
    setUp(parameters.first, parameters.second)

 *
 * Instances of this class are immutable. Use [Builder] to create instances.
 */
@Suppress("NAME_SHADOWING")
class Headers internal constructor(
  internal val namesAndValues: Array<String>,
) : Iterable<Pair<String, String>> {
  /** Returns the last value corresponding to the specified field, or null. */
  operator fun get(name: String): String? = commonHeadersGet(namesAndValues, name)

  /**

      }

    /**
     * Sets the public/private key pair used for this certificate. If unset a key pair will be
     * generated.
     */
    fun keyPair(keyPair: KeyPair) =
      apply {
        this.keyPair = keyPair
      }

    /**
     * Sets the public/private key pair used for this certificate. If unset a key pair will be
     * generated.
     */
    fun keyPair(

   * }
   * ```
   *
   * The first property of the pair is the adapter that was used, the second property is the value.
   */
  internal val generalNameDnsName = Adapters.IA5_STRING.withTag(tag = 2L)
  internal val generalNameIpAddress = Adapters.OCTET_STRING.withTag(tag = 7L)
  internal val generalName: DerAdapter<Pair<DerAdapter<*>, Any?>> =
    Adapters.choice(
      generalNameDnsName,