public boolean hasExpired(long now, long expireTime) {
    if (isExpiryUnitSeconds()) {
      // Units are seconds but the internal timestamps are milliseconds.
      // To prevent a needless reschedule, bump now by half a second.
      now += HALF_A_SECOND_IN_MILLIS;
    }
    return now >= expireTime;
  }
Return the given timestamp as milliseconds.
If the given secondsOrMillis is already millis then no conversion is needed.
geode-core/src/main/java/org/apache/geode/internal/cache/ExpiryTask.java