@Override
  protected void rollbackState(MasterProcedureEnv env, RegionStateTransitionState state)
    throws IOException, InterruptedException {
    // no rollback
    throw new UnsupportedOperationException();
  }
At end of timeout, wake ourselves up so we run again.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/TransitRegionStateProcedure.java