public void ensureDefaultAttributes() {
    Map<String, String> supportsAttributes = attributes.get(Supports.KEYWORD);
    for (Supports supportsProperty : Supports.values()) {
      String propertyName = supportsProperty.getPropertyName();
      if (! supportsAttributes.containsKey(propertyName)) {
        supportsAttributes.put(propertyName, supportsProperty.getDefaultValue());
      }
    }
  }
Set the default value of all type attributes which are not already specified.
ambari-server/src/main/java/org/apache/ambari/server/stack/ConfigurationInfo.java