我有 mongo 中的屬性列表，我正在查詢一些嵌套字段。這是我的代碼，public List<Brand> searchBrands(Request request) {    final MongoCollection<Document> collection = mongoDatabase.getCollection("shop");    final Document query = new Document();    final Document projection = new Document();    final List<Brand> brandList = new ArrayList<>();    query.append("_id", request.getId());    query.append("isActive", true);    if (request.Year() != null) {        query.append("attributes.name", "myYear");        query.append("attributes.value", request.getYear());    }    projection.append("brand.code", 1.0);    projection.append("brand.description", 1.0);    projection.append("_id", 0.0);    Block<Document> processBlock = document -> brandList.            add(Brand.builder().code(document.get("brand",Document.class).getString("code"))                    .description(document.get("brand",Document.class).getString("description"))                    .build());    collection.find(query).projection(projection).forEach(processBlock);    return brandList;}以上代碼正確返回結果，有 72 個具有相同品牌代碼的商品。但我想根據brand.code 獲取不同的內容，我該怎么做？