code: public static String listCustom() throws UnsupportedConfigurationException {
          String output = null;
          if (cms != null && !cms.isEmpty()) {
              if (cms.size() != 1) {
                  // the number of the custom encryption is more than one, an exception is thrown.
                  String message = composeMultipleCustomErrorMessage(cms);
                  throw new UnsupportedConfigurationException(message);
              }
              output = CustomUtils.toJSON(cms);
          }
          return output;
      }
docs: Returns the list of custom password encryption if exists.
  This method only works under the command line utility environment.
  
  @return list of the custom password encryption in JSON format
  @throws UnsupportedConfigurationException If there are multiple custom password encryption exists.