code: protected String doGetMessage(Locale locale, String key) { // no arguments
          // almost same as super's (seasar's) process
          // only changed is how to get bundle
          final MessageResourceBundle bundle = getBundle(locale);
          final String message = bundle.get(key);
          final Set<String> callerKeySet = createCallerKeySet();
          return resolveLabelVariableMessage(locale, key, message, callerKeySet); // also resolve label variables
      }
docs: ------------