private static void unlock(List<RegionStateNode> regionNodes) {
    for (ListIterator<RegionStateNode> iter = regionNodes.listIterator(regionNodes.size()); iter
      .hasPrevious();) {
      iter.previous().unlock();
    }
  }
Raw call to remote regionserver to get info on a particular region.
@throws IOException Let it out so can report this IOE as reason for failure
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManagerUtil.java