ObjectMapper写入一个数据，包含一个java.util.Date成员，报Expected class sun.util.calendar.BaseCalendar$Date but object was class java.util.Date错误。
这是hollow v2.1.0以下的一个bug，详见：
https://github.com/Netflix/hollow/issues/13
dkoszewnik commented on 31 Jan
| Thanks very much for the report! I verified the issue and released a fix in v2.1.1. |
有趣的是，将hollow替换成2.1.1，还是报这个错误，替换成2.2.1就好了
这句I verified the issue and released a fix in v2.1.1.像极了研发的口头禅‘下个版本修复’，承包了我一上午的笑点。