Javadoc
This code is for case where a hbase2 Master is starting for the first time. ZooKeeper is where
we used to keep table state. On first startup, read zookeeper and update hbase:meta with the
table states found in zookeeper. This is tricky as we'll do this check every time we startup
until mirroring is disabled. See the
#MIGRATE_TABLE_STATE_FROM_ZK_KEY flag. Original
form of this migration came in with HBASE-13032. It deleted all znodes when done. We can't do
that if we want to support hbase-1.x clients who need to be able to read table state out of zk.
See
MirroringTableStateManager.