@Override
    public void handleDegenerateRegion(HbckRegionInfo hi) throws IOException {
      errors.reportError(HbckErrorReporter.ERROR_CODE.DEGENERATE_REGION,
        "Region has the same start and end key.", getTableInfo(), hi);
    }
Returns descriptor common to all regions. null if are none or multiple!
hbase-server/src/main/java/org/apache/hadoop/hbase/util/HbckTableInfo.java