Re: JanusGraph database cache on distributed setup
It's great to hear that you have solved the previous problem.
Regarding contributing to the community, I would suggest you create a GitHub issue first, describing the problem and your approach there. This is not required but recommended. Then, you could create a pull request linking to that issue (note that you would also be asked to sign an individual CLA or corporate CLA once you create your first pull request in JanusGraph).
I am not 100% sure if I understand your question, but I guess you are asking what exactly is stored in that cache. Basically, that cache stores the raw data fetched from the storage backend. It does not have to be vertex - it could be vertex properties or edges. It might also contain deserialized data (See getCache() method in Entry.java). Note that in your case, since your cache is not local, it might be a better idea to store only the raw data but not the deserialized data to reduce the network overhead. To achieve that, you could override Entry::setCache method and let it do nothing. If you are interested in learning more about the "raw data", I wrote a blog Data layout in JanusGraph that you might be interested in.
Hope this helps.