I think MapsId falls under the same exception as PrimaryJoinKey, but @gbadner will be able to tell this for sure. See also this discussion: https://github.com/hibernate/hibernate-orm/commit/3218f6cc7df4f704eef5d70cc3514856e7d6f56d#diff-9aca9167532201db74410e7b0094d4a1R1834