Syslog messages should default to using the time at which they were received

Given a Syslog message that does not contain a timestamp:
%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet5/9 (75), with switch.fqdn.com GigabitEthernet2/4/21 (2)
we would expect the generated events to use the time at which the messages were received (by either OpenNMS or Minion in a distributed environment).

When a Syslog message is currently matched without any date components using the org.opennms.netmgt.syslogd.RadixTreeSyslogParser, the resulting timestamp in the event is null which triggers a org.postgresql.util.PSQLException: ERROR: null value in column "eventtime" violates not-null constraint.