What am I missing that makes this change a massive headache if just setting a flag gets the old behavior?
I haven't read the discussion but this seems like the obvious answer considering the flag only needs to be set during test.
Presumably this might miss some edge case (where something else also needs the flag?) though an explicit allow of the mockito agent in the jvm arg would have solved for that.
Nothing makes it a massive headache, but I think that Maven/Gradle don't make it as easy as they could and should.