tunnelCodec.readResponseHeaders(false)!!
          .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")