[jmx-scraper] Create weaver model for metrics of "activemq" target system

[mcmho]

This one is a sub-issue of #2072

Create a Weaver model for the "activemq" target systems of the metrics defined by jmx-scraper, so we can work to standardize them.

Here is an example of use that introduces a Weaver model to back the existing yaml files rather than directly replacing them: open-telemetry/opentelemetry-collector-contrib#40698

We should make this is backwards-compatible and does not break the existing functionalities while expressing telemetry data in weaver model.

[SylvainJuge]

I am currently working on improving/aligning jmx metrics between contrib and instrumentation for active mq with open-telemetry/opentelemetry-java-instrumentation#14278, so the current metrics (in contrib and in instrumentation) are about to change soon.

I am not familiar with weaver nor the expected benefits of having a weaver model for those metrics, but the changes introduced by the current work are breaking changes which the weaver might not be able to handle yet: adding/removing attributes, values conversions, units change, ...

JMX Metrics are defined in multiple places, but we are trying to simplify this, does the goal is to provide a way to migrate between those ?

• metrics in jmx-gatherer (contrib, groovy, deprecated)
• metrics in jmx-scraper (contrib, yaml, provided for migration from jmx-gatherer)
• metrics in instrumentation/jmx-metrics (instrumentation, yaml, should be the new reference)

I think it would however be interesting to have a weaver model after those changes are made, so future changes could be handled in a more graceful way.

Also, as the "reference" definitions themselves are now part of instrumentation I think it would be better to handle this directly into the java instrumentation repository.