code: public static String[] getNavigationAdditionalFields() {
          Configuration config = ConfigUtils.getCurrentConfig();
          if(config != null && config.containsKey(NAVIGATION_ADDITIONAL_FIELDS_CONFIG_KEY)) {
              return config.getStringArray(NAVIGATION_ADDITIONAL_FIELDS_CONFIG_KEY);
          } else {
              return new String[] {};
          }
      }
docs: Returns the list of additional fields that navigation items should extract from the item descriptor.