public List<RegionStateNode> getRegionsInTransition() {
    return new ArrayList<RegionStateNode>(regionInTransition.values());
  }
This is an EXPENSIVE clone. Cloning though is the safest thing to do. Can't let out original
since it can change and at least the load balancer wants to iterate this exported list. We need
to synchronize on regions since all access to this.servers is under a lock on this.regions.
@return A clone of current open or opening assignments.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStates.java