I have a project with 3 sub-projects. I want the 3 sub-projects to use the same dependencies versions so I factored all the versions in the root build.gradle:
This is not an exact answer to the question. I had the same concerns some time ago (had declared global vars and referred to them from build.gradle files).
I've found gradle-versions-plugin library, which resolved my concerns.
It will prompt with detailed info after ./gradlew dependencyUpdates