code: public void mapOptionFieldOption(String oldFieldName, String oldValue, String newValue) {
      Map<String, String> optionMap = optionFieldOptionMap.get(oldFieldName);
      if (optionMap == null) {
        optionMap = new HashMap<String, String>();
        optionFieldOptionMap.put(oldFieldName,  optionMap);
      }
      optionMap.put(oldValue, newValue);
    }
docs: etc.