upstream, the jmx exporter jar was moved from the maven thirdparty pom.xml to being curled down in the kafka Dockerfile because Prometheus does not plan to push anymore to Maven Central but only to GitHub releases. It is installed into a separate /opt/prometheus-jmx-exporter dir and referenced by the entry scripts using a $JMX_EXPORTER_HOMEenv var set in the Dockerfile.

Downstream we will need a slightly diverging build, including it in our RHEL distribution, and then set up the Dockerfile to move the jar into the same location as upstream and set the JMX_EXPORTER_HOME env var.