The default setting in /etc/opennms/opennms.properties is
if you create a custom config in /etc/opennms/opennms.properties.d/rrd.properties with content
The data collection with collectd works as expected and persists the performance measurements in the correct RRD files. The WebUI just shows the response time data which is not affected by this setting. It seems the WebUI is picking up the property from /etc/opennms/opennms.properties instead the overwritten one in /etc/opennms/opennms.properties.d/rrd.properties.
It is required to comment the property in opennms.properties with #org.opennms.rrd.storeByForeignSource=true.
Which seems not be the intended behavior introduced with