public void doNameNodeHAUpdate() {
    Map<String, Map<String, PropertyUpdater>> highAvailabilityUpdaters = createMapOfNameNodeHAUpdaters();

    // perform a single host update on these dynamically generated property names
    if (highAvailabilityUpdaters.get("hdfs-site").size() > 0) {
      doSingleHostExportUpdate(highAvailabilityUpdaters, clusterTopology.getConfiguration());
    }
  }
Perform export update processing for HA configuration for NameNodes.  The HA NameNode property
  names are based on the nameservices defined when HA is enabled via the Ambari UI, so this method
  dynamically determines the property names, and registers PropertyUpdaters to handle the masking of
  host names in these configuration items.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/BlueprintConfigurationProcessor.java