@Override
  public int hashCode() {
    return Objects.hashCode(mTtlIntervalStartTimeMs);
  }
@Test
  public void hashCodeTest() {
    TtlBucket firstBucket = new TtlBucket(0);
    TtlBucket secondBucket = new TtlBucket(0);
    TtlBucket thirdBucket = new TtlBucket(1);

    Assert.assertEquals(firstBucket.hashCode(), firstBucket.hashCode());
    Assert.assertEquals(firstBucket.hashCode(), secondBucket.hashCode());
    Assert.assertNotEquals(firstBucket.hashCode(), thirdBucket.hashCode());
  }