code: void persist(final String key, final String value, final boolean enableDisableMode, final boolean disable, final File file, final String realm) throws IOException, StartException {
          final PropertiesFileLoader propertiesHandler = realm == null ? new PropertiesFileLoader(file.getAbsolutePath(), null) :
                  new UserPropertiesFileLoader(file.getAbsolutePath(), null);
          try {
              propertiesHandler.start(null);
              if (realm != null) {
                  ((UserPropertiesFileLoader) propertiesHandler).setRealmName(realm);
              }
              Properties prob = propertiesHandler.getProperties();
              if (value != null) {
                  prob.setProperty(key, value);
              }
              if (enableDisableMode) {
                  prob.setProperty(key + "!disable", String.valueOf(disable));
              }
              propertiesHandler.persistProperties();
          } finally {
              propertiesHandler.stop(null);
          }
      }
docs: Implement the persistence handler for storing the user properties.