In the current age of fast deploying applications, using a Java Agent can help instrument you application without requiring code changes. With JMXTrans you can configure a set of exposed mbeans and the JMX Metrics Exporter will send them outside to a local netprobe waiting for the messages.
In Geneos we use StatsD for this inbound API and JMXTrans has a StatsD exporter natively in it.
I should note that this library works well for apps running on Hardware or VM’s. Containers can be a bit harder because you want to tag them with Pod Name and such so that they line up with other Geneos Metrics. However, perhaps the long term goal should be to support custom Mbeans in our own library (java_agent) here.
https://docs.itrsgroup.com/docs/geneos/5.10.0/data-collection/statsd-java-lib.html#Overview_..344