private Collection<Map<String, Map<String, PropertyUpdater>>> addYarnResourceManagerHAUpdaters(Collection<Map<String, Map<String, PropertyUpdater>>> updaters) {
    Collection<Map<String, Map<String, PropertyUpdater>>> highAvailabilityUpdaters =
      new LinkedList<>();

    // always add the statically-defined list of updaters to the list to use
    // in processing cluster configuration
    highAvailabilityUpdaters.addAll(updaters);

    // add the updaters for the dynamic HA properties, based on the HA config in hdfs-site
    highAvailabilityUpdaters.add(createMapOfYarnResourceManagerHAUpdaters());

    return highAvailabilityUpdaters;
  }
Creates a Collection of PropertyUpdater maps that include the Yarn ResourceManager HA properties, and
  adds these to the list of updaters used to process the cluster configuration.  The HA
  properties are based on the names of the Resource Manager instances defined in
  yarn-site, and so must be registered at runtime, rather than in the static list.

  This new Collection includes the statically-defined updaters,
  in addition to the HA-related updaters.

@param updaters a Collection of updater maps to be included in the list of updaters for
                  this cluster config update
@return A Collection of PropertyUpdater maps to handle the cluster config update
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/BlueprintConfigurationProcessor.java