In PR #3120 we added support for qualifiedBy and qualifiedByName. Our generic logic seems like it is putting the error line location on the method element itself. We should instead use the @SubclassMapping element for reporting the error.

This issue is a good issue to get started with MapStruct. If the original creator of the PR @EvaristeGalois11 is not interested in adding this, then I would invite someone from the community to give it a go.