private void mergeProperties(ConfigurationModule parent) {
    Collection<String> existingProps = new HashSet<>();
    Iterator<PropertyInfo> iter = info.getProperties().iterator();
    while (iter.hasNext()) {
      PropertyInfo prop = iter.next();
      existingProps.add(prop.getFilename() + "/" + prop.getName());
      if (prop.isDeleted()) {
        iter.remove();
      }
    }

    if (isExtensionEnabled()) {
      for (PropertyInfo prop : parent.info.getProperties()) {
        if (! existingProps.contains(prop.getFilename() + "/" + prop.getName())) {
          info.getProperties().add(prop);
        }
      }
    }
  }
Merge configuration properties with the configurations parent.

@param parent  parent configuration module
ambari-server/src/main/java/org/apache/ambari/server/stack/ConfigurationModule.java