@Override
            public boolean progress() {
              if (!isRegionStillOpening()) {
                LOG.warn("Open region aborted since it isn't opening any more");
                return false;
              }
              return true;
            }
Returns Instance of HRegion if successful open else null.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/handler/OpenRegionHandler.java