Mongodb java驱动程序获取字符串形式的结果，而不是bson对象

import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;

public class MongoDBExample {
    public static void main(String[] args) {
        // 连接到MongoDB数据库
        MongoClient mongoClient = new MongoClient("localhost", 27017);

        // 选择数据库和集合
        MongoDatabase database = mongoClient.getDatabase("mydb");
        MongoCollection<Document> collection = database.getCollection("mycollection");

        // 查询数据
        MongoCursor<Document> cursor = collection.find().iterator();
        while (cursor.hasNext()) {
            Document document = cursor.next();
            String jsonString = document.toJson();
            System.out.println(jsonString);
        }

        // 关闭连接
        mongoClient.close();
    }
}