@Override
    public void handleOverlapInRegionChain(HbckRegionInfo hi1, HbckRegionInfo hi2)
      throws IOException {
      errors.reportError(HbckErrorReporter.ERROR_CODE.OVERLAP_IN_REGION_CHAIN,
        "There is an overlap in the region chain.", getTableInfo(), hi1, hi2);
    }
Returns descriptor common to all regions. null if are none or multiple!
hbase-server/src/main/java/org/apache/hadoop/hbase/util/HbckTableInfo.java