使用java代码 mongo 的 morphia 日期分组统计：如：2017-03-23 现在是：2017-03-23 14：23：23 是怎么写的？求指教

Datastore datastore = simpleMongoDBDao.getDB();
Query query = datastore.createQuery(BcsBillListDOC.class);
query=query.filter("createTime >= ", DateUtil.getDateBystr(DateUtil.getSpecifiedDayBefore(date,7) + " 00:00:00"));
query=query.filter("payResult = ", 1 );
AggregationPipeline pipeline = datastore.createAggregation(BcsBillListDOC.class)
.match(query)
.group(
id(

这里不知道怎么写

                        ),
                        grouping("tradeMoney",sum("tradeMoney")),
                        grouping("createTime",first("createTime"))
                ).sort(Sort.descending("createTime"));
        Iterator<BillListGroupDOC> iterator = pipeline.aggregate(BillListGroupDOC.class);

http://blog.csdn.net/alen1985/article/details/9765457