/**
* Add a region from the head or tail to the List of regions to return.
*/
private void addRegionPlan(final MinMaxPriorityQueue<RegionPlan> regionsToMove,
final boolean fetchFromTail, final ServerName sn, List<RegionPlan> regionsToReturn) {
RegionPlan rp = null;
if (!fetchFromTail) rp = regionsToMove.remove();
else rp = regionsToMove.removeLast();
rp.setDestination(sn);
regionsToReturn.add(rp);
}