Noticed by anoop.hbase during review of
HBASE-18770, preCompact and preFlush can bypass normal processing by returning null. They are not bypasable by ordained route. We should shut down this avenue.
The preCompact at least may be new coming in with:
author zhangduo <firstname.lastname@example.org> Sat Apr 9 16:18:08 2016 +0800
committer zhangduo <email@example.com> Sun Apr 10 09:26:28 2016 +0800
HBASE-15527 Refactor Compactor related classes
Would have to dig in more to figure for sure.