.request(nextRequest)
          .build()
      tunnelCodec.skipConnectBody(response)

      when (response.code) {
        HttpURLConnection.HTTP_OK -> return null

        HttpURLConnection.HTTP_PROXY_AUTH -> {
          nextRequest = route.address.proxyAuthenticator.authenticate(route, response)
            ?: throw IOException("Failed to authenticate with proxy")

        .build()

    val fakeAuthChallengeResponse =
      Response
        .Builder()
        .request(proxyConnectRequest)
        .protocol(Protocol.HTTP_1_1)
        .code(HttpURLConnection.HTTP_PROXY_AUTH)
        .message("Preemptive Authenticate")
        .sentRequestAtMillis(-1L)
        .receivedResponseAtMillis(-1L)
        .header("Proxy-Authenticate", "OkHttp-Preemptive")
        .build()

        .proxyAuthenticator { _: Route?, response: Response? ->
          assertThat(response!!.request.method).isEqualTo("CONNECT")
          assertThat(response.code).isEqualTo(HttpURLConnection.HTTP_PROXY_AUTH)
          assertThat(response.request.url.host).isEqualTo("android.com")
          val challenges = response.challenges()
          assertThat(challenges[0].scheme).isEqualTo("OkHttp-Preemptive")

        .addHeader("Expires: " + formatDate(1, TimeUnit.HOURS))
        .code(responseCode)
        .body("ABCDE")
        .addHeader("WWW-Authenticate: challenge")
    when (responseCode) {
      HttpURLConnection.HTTP_PROXY_AUTH -> {
        builder.addHeader("Proxy-Authenticate: Basic realm=\"protected area\"")
      }

      HttpURLConnection.HTTP_UNAUTHORIZED -> {