WHAT

See if there are JMX metrics that indicate the OAuth method used, and expose that to Prometheus through the JMX config, so that it can be queried.

WHY

It would be useful to be able to see what percentage of clients generally use PLAIN OAuth in production. This would give us an indication of broker load on SSO (which has caused us problems previously). If a lot are using PLAIN, then this might be a consideration for keeping slightly more conservative connection rate limits.

HOW

1. Look for a metric in JMX that exposes this
2. Expose that through the kafka-metrics.yaml in the fleetshard project

DONE

Change rolled out to production, and metric queryable in the data plane Prometheus there.