As a clarification I'd like to propose my vision of this issue handling
and ask you to correct me, where I'm wrong:
AFAICT this is the full list of all of the Maven modules (including
plugins and libraries) - . What we need to do is to
traverse all of them and move all of the Maven (or not only Maven?)
libraries and plugins versions up to the maven-parent
(which they inherit OWOA) and to place, correspondingly, in
maven-dependencies.pom and maven-plugins.pom
which would be imported in the maven-parent.pom.
Thus, our dependencies would be overridden only by the apache.pom,
which is the parent of the maven-parent,
because inheritance has a higher priority than importing.
P.S.:  - I didn't quite understand the part here about the Reactor.
Could somebody tell me where to search info about this module?