How to navigate entity graph for entities returned by jqpl query in reporting module

Last year I asked a question about getting entities from jpql queries.

It works, but all the compositions and associations are null. I read somewhere (can’t find the ticket anyomre) that you have to be specific on what fields to retrieve in jpql queries. But how to do this for entities?

This question could be rephrased to:

How to retrieve attached entities for reporting.

I don’t really understand why the reporting module would work with detached entities. We are in the core module so navigation over entity graphs would be simple.