@Override
  protected void toStringState(StringBuilder builder) {
    super.toStringState(builder);
    RegionTransitionState ts = this.transitionState;
    if (!isFinished() && ts != null) {
      builder.append(":").append(ts);
    }
  }
Leave here only for checking if we can successfully start the master.
@deprecated Do not use any more.
@see TransitRegionStateProcedure
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionTransitionProcedure.java