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")

          if ("close".equals(response.header("Connection"), ignoreCase = true)) {
            return nextRequest