private RegionInfo getRegionInfo(TableName tableName, byte[] row) throws IOException {
    RegionInfo regionInfo =
      TEST_UTIL.getConnection().getRegionLocator(tableName).getRegionLocation(row).getRegion();
    assertNotNull(regionInfo);
    return regionInfo;
  }
Take last byte and add one to it.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/janitor/TestCatalogJanitorCluster.java