At least at http://docs.opennms.org/opennms/releases/17.0.0/guide-admin/guide-admin.html#_provisioning a picture is missing.
4.3.1. Provisioning the SNMP Configuration
OpenNMS requires that the SNMP configuration to be properly setup for your network in order to properly understand Network and Node topology as well as to automatically enabled performance data collection. Network topology is updated as nodes (a.k.a. devices or hosts) are provisioned. Navigate to the Admin/Configure SNMP Community Names as shown below.
Provisiond includes an option to add community information in the Single Node provisioning interface. This, is equivalent of entering a single IP address in the screen with the convenience of setting the community string at the same time a node is provisioned. See the Quick Node Add feature below for more details about this capability.
Here below, we are speaking about a screen, but which screen?
This screen sets up SNMP within OpenNMS for agents listening on IP addresses 10.1.1.1 through 10.254.254.254. These settings are optimized into the snmp-configuration.xml file. Optimization means that the minimal configuration possible will be written. Any IP addresses already configured that are eclipsed by this range will be removed. Here is the resulting configuration.