maxIdleConnections: Int = 5,
    keepAliveDuration: Long = 5,
    timeUnit: TimeUnit = TimeUnit.MINUTES,
    taskRunner: TaskRunner = TaskRunner.INSTANCE,
    connectionListener: ConnectionListener = ConnectionListener.NONE,
    readTimeoutMillis: Int = 10_000,
    writeTimeoutMillis: Int = 10_000,
    socketConnectTimeoutMillis: Int = 10_000,
    socketReadTimeoutMillis: Int = 10_000,
    pingIntervalMillis: Int = 10_000,

    @Volatile private var queryParamsNameToRedact = emptySet<String>()

    @set:JvmName("level")
    @Volatile
    var level = Level.NONE

    enum class Level {
      /** No logs. */
      NONE,

      /**
       * Logs request and response lines.
       *
       * Example:
       * ```
       * --> POST /greeting http/1.1 (3-byte body)
       *

    val source = this.source!!
    val sink = this.sink!!
    socket.soTimeout = 0 // HTTP/2 connection timeouts are set per-stream.
    val flowControlListener = connectionListener as? FlowControlListener ?: FlowControlListener.None
    val http2Connection =
      Http2Connection.Builder(client = true, taskRunner)
        .socket(socket, route.address.url.host, source, sink)
        .listener(this)
        .pingIntervalMillis(pingIntervalMillis)

    route: Route?,
    response: Response,
  ): Request?

  companion object {
    /** An authenticator that knows no credentials and makes no attempt to authenticate. */
    @JvmField
    val NONE: Authenticator = AuthenticatorNone()

    private class AuthenticatorNone : Authenticator {
      override fun authenticate(
        route: Route?,
        response: Response,
      ): Request? = null
    }

    @Override public EventListener create(Call call) {
      if (Math.random() < 0.10) {
        return new MetricsEventListener(call);
      } else {
        return EventListener.NONE;
      }
    }
  };

  ...
}
```

### Events with Failures

        .build(),
    )
    val response = getResponse(newRequest("/"))
    assertThat(response.code).isEqualTo(200)
    assertThat(response.message).isEqualTo("OK")
    assertContent(
      "STR;FFMJ2;Frankfurt;RTCM 2.1;1(1),3(19),16(59);0;GPS;GREF;DEU;50.12;8.68;0;1;GPSNet V2.10;none;N;N;560;Demo\nENDSOURCETABLE",
      response,
    )

  const val TYPE_SETTINGS = 0x4
  const val TYPE_PUSH_PROMISE = 0x5
  const val TYPE_PING = 0x6
  const val TYPE_GOAWAY = 0x7
  const val TYPE_WINDOW_UPDATE = 0x8
  const val TYPE_CONTINUATION = 0x9

  const val FLAG_NONE = 0x0
  const val FLAG_ACK = 0x1 // Used for settings and ping.
  const val FLAG_END_STREAM = 0x1 // Used for headers and data.
  const val FLAG_END_HEADERS = 0x4 // Used for headers and continuation.

    assertThat(get(url).body.string()).isEqualTo("B")
    assertThat(server.takeRequest().headers["If-None-Match"]).isNull()
    assertThat(server.takeRequest().headers["If-None-Match"]).isEqualTo("v1")
    assertThat(server.takeRequest().headers["If-None-Match"]).isEqualTo("v1")
    assertThat(server.takeRequest().headers["If-None-Match"]).isEqualTo("v2")
  }

  @Test
  fun combinedCacheHeadersCanBeNonAscii() {

      // will not be transmitted.
      val conditionName: String
      val conditionValue: String?
      when {
        etag != null -> {
          conditionName = "If-None-Match"
          conditionValue = etag
        }

        lastModified != null -> {
          conditionName = "If-Modified-Since"
          conditionValue = lastModifiedString
        }

      field = value
    }

  private var serverSocket: ServerSocket? = null
  private var sslSocketFactory: SSLSocketFactory? = null
  private var clientAuth = CLIENT_AUTH_NONE

  /**
   * The dispatcher used to respond to HTTP requests. The default dispatcher is a [QueueDispatcher],
   * which serves a fixed sequence of responses from a [queue][enqueue].
   *