public static KeepDeletedCells getValue(String val) {
    return valueOf(val.toUpperCase());
  }
Deleted Cells are retained until the delete marker expires due to TTL. This is useful when TTL
is combined with MIN_VERSIONS and one wants to keep a minimum number of versions around but at
the same time remove deleted cells after the TTL.
hbase-client/src/main/java/org/apache/hadoop/hbase/KeepDeletedCells.java