boolean isInViolation(SpaceQuotaSnapshot snapshot) {
    if (snapshot == null) {
      return false;
    }
    return snapshot.getQuotaStatus().isInViolation();
  }
Checks if the given <code>snapshot</code> is in violation, allowing the snapshot to be null. If
the snapshot is null, this is interpreted as no snapshot which implies not in violation.
@param snapshot The snapshot to operate on.
@return true if the snapshot is in violation, false otherwise.
hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/SpaceQuotaRefresherChore.java