From Marek Kopecky: "forward.compatibility profile was used by QE only. We used this profile for checks of new resteasy client (new TS) with old server. Some new test checks features that are not present in old server, so this profile basically excludes all these tests annotated by NotForForwardCompatibility annotation. But this had high maintenance, and there were no benefit (this kind of test didn't show any error/regression for many years), so QE don't test this anymore. So this profile is not used by QE now (and can be removed)."