Both submodules and parent pom has app.version property. Seems like having it in the parent should suffice. Not changing it for 3.5 release. something that should be addressed in next release
its in the sub-module if its a subset. For example, there are no realtime database plugins so the database submodule only has batch artifacts as its parents.
This is intentional. Otherwise, the realtime plugins will show up as plugins for the batch artifacts (not in the UI, but in the REST calls).