Comment 3 for bug 1782340

If, by "API group" you mean API-SIG that's not what the guidance has been. The guidance has been that if a non-500 response changes, that's a new microversion. In this case a request with an alien field that resulted in a 200 or 204 could become a 400 with the proposed fix in place.

With my api-sig hat on, that means we need a microversion.

With my "how did I ever become an adjuticator of microversions, kill me now" hat on, I don't care.