List<GcpAddress> getAddresses() {
        try {
            return RetryUtils.retry(this::fetchGcpAddresses, RETRIES, NON_RETRYABLE_KEYWORDS);
        } catch (RestClientException e) {
            handleKnownException(e);
            return emptyList();
        }
    }
@Test(expected = Exception.class)
    public void getAddressesUnknownException() {
        // given
        Label label = null;
        RestClientException exception = new RestClientException("unknown", HttpURLConnection.HTTP_INTERNAL_ERROR);
        given(gcpComputeApi.instances(CURRENT_PROJECT, CURRENT_ZONE, label, ACCESS_TOKEN)).willThrow(exception);

        GcpConfig gcpConfig = GcpConfig.builder().setLabel(label).build();
        GcpClient gcpClient = new GcpClient(gcpMetadataApi, gcpComputeApi, gcpAuthenticator, gcpConfig);

        // when
        gcpClient.getAddresses();

        // then
        // throws exception
    }