docs: public static Object getFieldOnSuper(Class senderClass, Object receiver, String messageName) throws Throwable {
          try {
              if (receiver instanceof Class) {
                  return InvokerHelper.getAttribute(receiver, messageName);
              } else {
                  MetaClass mc = ((GroovyObject) receiver).getMetaClass();
                  return mc.getAttribute(senderClass, receiver, messageName, true);
              }
          } catch (GroovyRuntimeException gre) {
              throw unwrap(gre);
          }
      }