private CompletionStage<RestResponse> backupStatus(RestRequest request) {
      return statusOperation(request, SITES_STATUS);
   }
@Test
   public void testInvalidSite() {
      RestClient client = clientPerSite.get(LON);
      RestCacheClient cache = client.cache(CACHE_1);
      assertStatus(404, cache.backupStatus("invalid-site"));
   }