private static boolean isRegionStillOpening(RegionInfo regionInfo,
    RegionServerServices rsServices) {
    byte[] encodedName = regionInfo.getEncodedNameAsBytes();
    Boolean action = rsServices.getRegionsInTransitionInRS().get(encodedName);
    return Boolean.TRUE.equals(action); // true means opening for RIT
  }
Returns Instance of HRegion if successful open else null.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/handler/OpenRegionHandler.java