private void verifyMiddleHole(CatalogJanitor janitor) throws IOException {
    // Verify middle holes
    RegionInfo firstRegion = getRegionInfo(T3, "".getBytes());
    RegionInfo secondRegion = getRegionInfo(T3, "bbb".getBytes());
    RegionInfo thirdRegion = getRegionInfo(T3, "ccc".getBytes());
    TEST_UTIL.getHBaseCluster().getMaster().getAssignmentManager().getRegionStateStore()
      .deleteRegion(secondRegion);
    LinkedList<Pair<RegionInfo, RegionInfo>> holes = getHoles(janitor, T3);
    Pair<RegionInfo, RegionInfo> regionInfoRegionInfoPair = holes.getFirst();
    assertTrue(regionInfoRegionInfoPair.getFirst().getTable().equals(T3));
    assertTrue(regionInfoRegionInfoPair.getSecond().getTable().equals(T3));
    assertTrue(
      regionInfoRegionInfoPair.getFirst().getEncodedName().equals(firstRegion.getEncodedName()));
    assertTrue(
      regionInfoRegionInfoPair.getSecond().getEncodedName().equals(thirdRegion.getEncodedName()));
  }
Take last byte and add one to it.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/janitor/TestCatalogJanitorCluster.java