@Override
    public Collection<String> getRequiredHostGroups(String propertyName,
                                                    String origValue,
                                                    Map<String, Map<String, String>> properties,
                                                    ClusterTopology topology) {

      return Collections.emptySet();
    }
PropertyUpdater implementation that will always return the original
  value for the updateForClusterCreate() method.
  This updater type should only be used in cases where a given
  property requires no updates, but may need to be considered
  during the Blueprint export process.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/BlueprintConfigurationProcessor.java