根据内部键，mongodb和Java中的值检索嵌入式文档

Question

我的文件如下

{
    "name" : "kamala",
    "condition" : "nice",
    "flows" : [ 
        {
            "Date" : "2018-07-18",
            "formulae" : {
                "less" : "5",
                "greater" : "3",
                "flat" : "4"
            }
        }, 
        {
            "Date" : "2018-07-12",
            "formulae" : {
                "team" : "7",
                "nature" : "4"
            }
        }
    ]
}

我必须基于"formulae"，"name" : "kamala"

来检索"Date" : "2018-07-18"内部的值。