code: public static ResourceBundle getBundle(ResourceBundle self, String bundleName) {
          return getBundle(self, bundleName, Locale.getDefault());
      }
docs: Works exactly like ResourceBundle.getBundle(String).  This is needed
  because the java method depends on a particular stack configuration that
  is not guaranteed in Groovy when calling the Java method.
  
  @param self       placeholder variable used by Groovy categories; ignored for default static methods
  @param bundleName the name of the bundle.
  @return the resource bundle
  @see java.util.ResourceBundle#getBundle(java.lang.String)
  @since 1.6.0