code: public static ResourceBundle getMessageBundle() {
      try {
        ResourceBundle bundle = ResourceBundle.getBundle(MESSAGE_BUNDLE);
        ResourceBundle fallbackBundle = ResourceBundle.getBundle(MESSAGE_BUNDLE, Locale.ENGLISH);
        return new ResourceBundleWithFallback(bundle, fallbackBundle);
      } catch (MissingResourceException e) {
        return ResourceBundle.getBundle(MESSAGE_BUNDLE, Locale.ENGLISH);
      }
    }
docs: Gets the ResourceBundle (i18n strings) for the default language of the user's system.