问题描述：有个List对象，如下：
List<Map<String,Object>> query = new ArrayList<Map<String,Object>>
Json视图下的例子数据为：
[

{
    "customer_attribute": "1",
    "customer_attribute_no": "0101019",
    "group_no": 1
},
{
    "customer_attribute": "2",
    "customer_attribute_no": "A001",
    "group_no": 1
},
{
    "customer_attribute": "3",
    "customer_attribute_no": "AA001",
    "group_no": 2
}

]
现在需求是将原List中数据构建成：
[

{
    "attributelist": [
        {
            "customer_attribute": "1",
            "customer_attribute_no": "0101019"
        },
        {
            "customer_attribute": "2",
            "customer_attribute_no": "A001"
        }
    ],
    "group_no": 1
},
{
    "attributelist": [
        {
            "customer_attribute": "3",
            "customer_attribute_no": "AA001"
        }
    ],
    "group_no": 2
}

]，
我的想法是将原来的List中的多个Map先用stream中的flatMap()合成一个Map，让后对这个Map中以“group_no”为key进行分组，分组后将各自新Map中的“customer_attribute”构建新的key为“attributelist”的List，从而实现。但我太清楚具体该如何编写代码，有前辈可以指导写一下参考吗？万分感激！