public Set<String> assembleAllWatchKeys(String appId, String clusterName, String namespace,
                                          String dataCenter) {
    Multimap<String, String> watchedKeysMap =
        assembleAllWatchKeys(appId, clusterName, Sets.newHashSet(namespace), dataCenter);
    return Sets.newHashSet(watchedKeysMap.get(namespace));
  }
@Test
  public void testAssembleAllWatchKeysWithOneNamespaceAndSomeDC() throws Exception {
    Set<String> watchKeys =
        watchKeysUtil.assembleAllWatchKeys(someAppId, someDC, someNamespace, someDC);

    Set<String> clusters = Sets.newHashSet(defaultCluster, someDC);

    assertEquals(clusters.size(), watchKeys.size());
    assertWatchKeys(someAppId, clusters, someNamespace, watchKeys);
  }