Like Simon said, I think this is more useful for people working on Elasticsearch then it is for folks working with Elasticsearch because I think it includes all the internal APIs.
I think it'd be useful for Java users if we had a jar for the high level REST client rather than depending on Elasticsearch core and we generated the report for that jar. And we do want to do that, we just haven't got to it because it is a lot of work to decouple all the things.
It'd also be the useful if we had a plugin API jar. We don't and that is even further away from happening. At this point we don't consider any of the plugin interfaces set in stone though. So I expect them to change in minor releases. At least for a while. I've been saying for a few years now that a real, semvered plugin API is at least two years away. It still is, I think.
I think it'd be useful to point it at the low level rest client right now but that is about the only part of Elasticsearch that'd give reasonable results.