private lateinit var serverIpv6: MockWebServer

  private val listener = RecordingEventListener()
  private lateinit var client: OkHttpClient
  private lateinit var url: HttpUrl

  /**
   * This is mutable and order matters. By default, it contains [IPv4, IPv6]. Tests may manipulate
   * it to prefer IPv6.
   */
  private var dnsResults = listOf<InetAddress>()

  @BeforeEach
  internal fun setUp() {

    internal var method: String
    internal var headers: Headers.Builder
    internal var body: RequestBody? = null
    internal var cacheUrlOverride: HttpUrl? = null

    /** A mutable map of tags, or an immutable empty map if we don't have any. */
    internal var tags = mapOf<KClass<*>, Any>()

    constructor() {
      this.method = "GET"
      this.headers = Headers.Builder()
    }

  private var writerTask: Task? = null

  /** Null until this web socket is connected. Only accessed by the reader thread. */
  private var reader: WebSocketReader? = null

  // All mutable web socket state is guarded by this.

  /** Null until this web socket is connected. Note that messages may be enqueued before that. */
  private var writer: WebSocketWriter? = null

 *  Fix: `OkHttpClient` no longer implements `Cloneable`. It never should have; the class is
    immutable. This is left over from OkHttp 2.x (!) when that class was mutable. We're using the
    5.x upgrade as an opportunity to remove very obsolete APIs.
 *  Fix: Recover gracefully when Android's `NativeCrypto` crashes with `"ssl == null"`. This occurs