private byte[] makeDummyData(int size) {
    byte[] dummyData = new byte[size];
    Bytes.random(dummyData);
    return dummyData;
  }
Creates a 3 day old hfile and an 1 day old hfile then sets expiry to 2 days. Verifies that the
3 day old hfile is removed but the 1 day one is still present after the expiry based cleaner is
run.
hbase-server/src/test/java/org/apache/hadoop/hbase/mob/TestExpiredMobFileCleaner.java