@JvmField @Rule
  val serverRule = MockWebServerRule()
  private lateinit var client: OkHttpClient

  private val localhost: HandshakeCertificates by lazy {
    // Generate a self-signed cert for the server to serve and the client to trust.
    val heldCertificate =
      HeldCertificate.Builder()
        .addSubjectAlternativeName("localhost")
        .build()
    return@lazy HandshakeCertificates.Builder()