Project query in Springboot didn't work well

In SpringBoot Applicaton,when i query mongo like this in MongoRepository:

@Aggregation({
            "{$match:{createUid: ?0}}",
            "{$lookup: {from: 't_user',localField: 'contactUid',foreignField:'_id',as: 'contact'}}",
            "{$addFields: {contact:{$arrayElemAt: ['$contact',0]} }}",
            "{$project: { 'contact.password': 0,'contact.salt': 0}}",
    })
List<HashMap> searchSentAddContacts(ObjectId createUid);

The $Project action just set contact.password and contact.salt to null in final result list,didn't exclude the fields. But when i use the same query in mongo console,it works well.'contact.password' and 'contact.salt' are gone in result.

Here is my collection strcut: 't_add_contacts':

[
  {
    "_id": {"$oid": "66ef75795e8146631d0658bc"},
    "_class": "org.tzx.xim.entity.AddContactsEntity",
    "addType": 0,
    "contactUid": {"$oid": "66ef75505e8146631d0658bb"},
    "createTime": {"$date": "2024-09-22T01:40:09.665Z"},
    "createUid": {"$oid": "66ef75425e8146631d0658ba"},
    "updateTime": {"$date": "2024-09-22T01:40:09.665Z"}
  }
]

't_user':

[
  {
    "_id": {"$oid": "66ef75425e8146631d0658ba"},
    "_class": "org.tzx.xim.entity.UserEntity",
    "createTime": {"$date": "2024-09-22T01:39:14.569Z"},
    "loginName": "user1",
    "nickName": "haha1",
    "password": "123456",
    "salt": "awsddqwdqwd",
    "updateTime": {"$date": "2024-09-22T01:39:14.569Z"}
  }
]

Thanks everyone!

Query collection 't_add_contacts' and join part of collection 't_user'.