记一个坑-list.addAll()后，修改新list的内容，旧list也会跟着改

问题代码：

public static void main(String[] args) throws Exception{
        Map<String,Object> map = new HashMap<>();
        map.put("a",1);
        List<Map<String,Object>> l1 = new ArrayList<>();
        l1.add(map);
        List<Map<String,Object>> l2 = new ArrayList<>();
        System.err.println("l1:" + new Gson().toJson(l1));
        System.err.println("l2:" + new Gson().toJson(l2));
        l2.addAll(l1);
        for (Map<String, Object> mapUtil : l2) {
            mapUtil.put("b",1);
        }
        System.err.println("l1:" + new Gson().toJson(l1));
        System.err.println("l2:" + new Gson().toJson(l2));
    }

打印：

l1:[{"a":1}]
l2:[]
l1:[{"a":1,"b":1}]
l2:[{"a":1,"b":1}]

可以看到我明显改的是l2，l1怎么也变了呢，原因就在 addAll()
修改代码：

public static void main(String[] args) throws Exception{
        Map<String,Object> map = new HashMap<>();
        map.put("a",1);
        List<Map<String,Object>> l1 = new ArrayList<>();
        l1.add(map);
        List<Map<String,Object>> l2 = new ArrayList<>();
        System.err.println("l1:" + new Gson().toJson(l1));
        System.err.println("l2:" + new Gson().toJson(l2));
        l2 =(List<Map<String,Object>>) SerializationUtils.clone((Serializable) l1);
        for (Map<String, Object> mapUtil : l2) {
            mapUtil.put("b",1);
        }
        System.err.println("l1:" + new Gson().toJson(l1));
        System.err.println("l2:" + new Gson().toJson(l2));
    }

打印：

l1:[{"a":1}]
l2:[]
l1:[{"a":1}]
l2:[{"a":1,"b":1}]

完美