public static KeyValue createFirstOnRow(final byte[] row, final long ts) {
    return new KeyValue(row, null, null, ts, KeyValue.Type.Maximum);
  }
Creates a KeyValue that is smaller than all other KeyValues that are older than the passed
timestamp.
@param row - row key (arbitrary byte array)
@param ts  - timestamp
@return First possible key on passed <code>row</code> and timestamp.
hbase-common/src/main/java/org/apache/hadoop/hbase/KeyValueUtil.java