code: static boolean equalsImpl(Map<?, ?> map, Object object) {
      if (map == object) {
        return true;
      } else if (object instanceof Map) {
        Map<?, ?> o = (Map<?, ?>) object;
        return map.entrySet().equals(o.entrySet());
      }
      return false;
    }
docs: An implementation of {@link Map#equals}.