MongoDB SNMP Traps are missing values for Hostname (4379367)

MongoDB SNMP Traps are missing values for Hostname. The OID Value is not being set for MongoDB alarms unlike other database agent Types. 

The value for hostname comes from the monitoredHost property on the alarm object (agent in the case of the agent health state rule)

The agent does not set the monitored host on the agent object because a MongoDB target is almost never a single instance. It is a replica set (or even sharded cluster) running across several hosts.

This is by design