How to repeat:
Take an AS4 instance into inventory (i used the JOPR server itself). Expand the left nav to reveal the 3 Tomcat Connector resources, click on one of them. Click Monitor->Tables tab. Note that the metrics are empty and remain that way over many metric collection intervals. These metrics should be collected. Note: i brought up a 2.2GA server and saw that the metrics are in fact collected on that version, so this is something that broke during 2.3 development.