public static boolean isExpiredSnapshot(long snapshotTtl, long snapshotCreatedTime,
    long currentTime) {
    return snapshotCreatedTime > 0 && snapshotTtl > HConstants.DEFAULT_SNAPSHOT_TTL
      && snapshotTtl < TimeUnit.MILLISECONDS.toSeconds(Long.MAX_VALUE)
      && (snapshotCreatedTime + TimeUnit.SECONDS.toMillis(snapshotTtl)) < currentTime;
  }
Method to check whether TTL has expired for specified snapshot creation time and snapshot ttl.
NOTE: For backward compatibility (after the patch deployment on HMaster), any snapshot with ttl
0 is to be considered as snapshot to keep FOREVER. Default ttl value specified by
{@link HConstants#DEFAULT_SNAPSHOT_TTL}
@return true if ttl has expired, or, false, otherwise
hbase-server/src/main/java/org/apache/hadoop/hbase/snapshot/SnapshotDescriptionUtils.java