Answered on community slack - please don't cross post - this just
generates duplicate work and leaves some places with open ends. Some
quotes copied from there (might lack context, but give some food for
thoughts for anyone coming along later):
I've never heard the term
"war-core-ext" - but the "ext" part points to
something that's indeed no longer there. Not sure if that's since 7.4
or 7.3
What do you intend to do with it?
and
There are plenty of options depending on
the problem to be solved. There is no more "overriding of core
classes", but "implement public extension
points".
Problems that you used to solve through core
overrides should not be solved that way any more - it's a maintenance
nightmare (for you) and bypassing any APIs.
are the core parts.
In short: Don't plan on modifying anything that bypasses APIs and
extension points. "ext" style plugins introduce a
maintenance nightmare and drive up your upgrade cost, and with it your
resistance to upgrades. That's the reason they don't exist any more.
