private static void addUnitPropertyUpdaters() {
    Map<String, List<UnitValidatedProperty>> propsPerConfigType = UnitValidatedProperty.ALL
      .stream()
      .collect(groupingBy(UnitValidatedProperty::getConfigType));
    for (String configType : propsPerConfigType.keySet()) {
      Map<String, PropertyUpdater> unitUpdaters = new HashMap<>();
      for (UnitValidatedProperty each : propsPerConfigType.get(configType)) {
        unitUpdaters.put(each.getPropertyName(), new UnitUpdater(each.getServiceName(), each.getConfigType()));
      }
      mPropertyUpdaters.put(configType, unitUpdaters);
    }
  }
A topology independent updater which provides a default implementation of getRequiredHostGroups
since no topology related information is required by the updater.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/BlueprintConfigurationProcessor.java