code: final long getDerivedJmsDeliveryTime() {
          long ts = getTimestamp().longValue();
          long dd = getDeliveryDelay().longValue();
          if ((ts <= 0) || (dd <= 0)) {
              return 0;
          }
          else {
              return (ts + dd);
          }
      }
docs: Return the derived JmsDeliveryDelayTime for a non-JMS/MQ produced message.
  The value is derived from the Timestamp and DeliveryDelay values.
  d336582 - now want to return 0 if Timestamp or TimeToLive are 'not set'.
  
  @return long The JmsDeliveryDelayTime value for the JMS message.