Map 嵌套map 遍历

private static Map flatten(final String key, final Map map,
        final Map result) {
    final Set> entries = map.entrySet();
    if (!entries.isEmpty()) {
        for (final Map.Entry entry : entries) {
            //iterate over entries
            final String currKey = key + (key.isEmpty() ? "" : '.') + entry.getKey();
           //append current key to previous key, adding a dot if the previous key was not an empty String
            final Object value = entry.getValue();
            if (value instanceof Map) {//current value is a Map
                flatten(currKey, (Map) value, result);//flatten Map
            } else if (value instanceof List) {//current value is a List
                final List