- Introduce support for CEL optionals (see [CEL spec proposal 246](https://github.com/google/cel-spec/wiki/proposal-246)).
  This feature will not be fully enabled until a future Kubernetes release (likely to be v1.29), but is added in v1.28 to enable
  safe rollback on downgrade. ([#118339](https://github.com/kubernetes/kubernetes/pull/118339), [@jpbetz](https://github.com/jpbetz)) [SIG API Machinery, Auth, Cloud Provider and Testing]

 app/v1beta2 group version, because the controllers in the workloads API do not handle
 selector mutation in
 a consistent way. This restriction may be lifted in the future, but
 it is likely that that selectors will remain immutable after the move to v1.
 You can continue to use code that depends on mutable selectors by calling
 the apps/v1beta1 API in this release, but you should start planning for code