On a test lab, I was testing Horizon 20 as I usually do when there is a new release, and I discovered the following problem:
OpenNMS is scheduling SNMP data collection for every single IP/service pair that matches a collection package regardless of the isSnmpPrimary flag on the ipInterface table.
The above is true no matter if the nodes are behind a Minion or directly managed by OpenNMS.
This might affect other services, but I've only noted this on SNMP, which is the one that for sure should use the concept of the primary interface.
This never happened before, as until H19, the SNMP Collector (and Collectd in general) was respecting the proper scheduling of the services using the primary IP address.