code: private boolean isAvailable(String... bundleNames) {
  
      for (String name : bundleNames) {
        ResourceBundle.getBundle(name, AbstractNlsMessage.LOCALE_ROOT);
      }
      return true;
    }
docs: This method verifies that the given {@code bundleNames} are available {@link ResourceBundle}s.
  
  @param bundleNames are the {@link ResourceBundle#getBundle(String) bundle names}.
  @return {@code true}.