code: public ResourceBundle toResourceBundle(Class<? extends NlsBundle> bundleClass) {
  
      Hashtable<String, String> bundleProperties = new Hashtable<>();
      for (Method method : bundleClass.getMethods()) {
        if (isNlsBundleMethod(method, false)) {
          String key = getKey(method);
          String message = getMessage(method);
          bundleProperties.put(key, message);
        }
      }
      GenericResourceBundle bundle = new GenericResourceBundle(bundleProperties);
      return bundle;
    }
docs: Converts the given {@link NlsBundle} class to a {@link ResourceBundle}.
  
  @param bundleClass is the class reflecting a {@link NlsBundle}.
  @return a {@link ResourceBundle} with the key/value pairs of the given {@code bundleClass} for
  {@link java.util.Locale#ROOT}.
  @since 4.0.0