On 1.12, if I add a new data collection group with new metrics and new resource types, OpenNMS starts to collect the new data after executing "touch $OPENNMS_HOME/etc/datacollection-config.xml" (without the quotes), and the WebUI is updated showing the new resources. That way you can see the graphs associated with new resource types without restarting OpenNMS.
On 14.0.0, that has stopped working for some reason and I was able to reproduce it using the following procedure:
1) Brand new OpenNMS 14 installed on a CentOS VM
2) Edit etc/datacollection/cisco.xml and remove some resource types and their metrics (and of course, update the systemDefs)
3) Start OpenNMS and add a Cisco device
4) Check that the resource types are correct with the current cisco.xml
5) After a while, restore the original content (which emulates the addition of new metrics and resource types) and execute "touch etc/datacollection-config.xml".
6) The RRD are created and they are being updated without issues.
7) Go to the WebUI and see the resources
Expected result: the new resources must be shown there.
Current result: there are no changes on the WebUI for the resources associated with new resource types.