Action required for custom scheduler plugin developers:
  Plugins **have to** implement a QueueingHint for Pod/Update event if the rejection from them could be resolved by updating unscheduled Pods themselves.
  Example: suppose you develop a custom plugin that denies Pods that have a `schedulable=false` label. 

* For Deployment, ReplicaSet, and DaemonSet, selectors are now immutable when updating via the new `apps/v1beta2` API. For backward compatibility, selectors can still be changed when updating via `apps/v1beta1` or `extensions/v1beta1`. ([#50719](https://github.com/kubernetes/kubernetes/pull/50719), [@crimsonfaith91](https://github.com/crimsonfaith91))

- Added consistent vanity import to files and provided tooling for verifying and updating them. ([#120642](https://github.com/kubernetes/kubernetes/pull/120642), [@jcchavezs](https://github.com/jcchavezs))

- Fix problem in updating VolumeAttached in node status ([#112303](https://github.com/kubernetes/kubernetes/pull/112303), [@xing-yang](https://github.com/xing-yang)) [SIG Apps]

- Fix problem in updating VolumeAttached in node status ([#112302](https://github.com/kubernetes/kubernetes/pull/112302), [@xing-yang](https://github.com/xing-yang)) [SIG Apps]

- The `matchLabelKeys/mismatchLabelKeys` feature is introduced to the hard/soft `PodAffinity/PodAntiAffinity`. ([#116065](https://github.com/kubernetes/kubernetes/pull/116065), [@sanposhiho](https://github.com/sanposhiho))
- When updating a CRD, per-expression cost limit check are now skipped for `x-kubernetes-validations` rules of versions that are not mutated. ([#121460](https://github.com/kubernetes/kubernetes/pull/121460), [@jiahuif](https://github.com/jiahuif))

- Kubeadm: improved retries when updating node information, in case `kube-apiserver` is temporarily unavailable ([#114176](https://github.com/kubernetes/kubernetes/pull/114176), [@QuantumEnergyE](https://github.com/QuantumEnergyE))

- Metrics for `RetroactiveDefaultStorageClass` feature are now available. To see an attempt count for updating PVC retroactively with a default StorageClass see `retroactive_storageclass_total` metric and for total numer of errors see `retroactive_storageclass_errors_total`. ([#113323](https://github.com/kubernetes/kubernetes/pull/113323), [@RomanBednar]...

- Fix problem in updating VolumeAttached in node status ([#112304](https://github.com/kubernetes/kubernetes/pull/112304), [@xing-yang](https://github.com/xing-yang)) [SIG Apps]

- Fix problem in updating VolumeAttached in node status ([#112305](https://github.com/kubernetes/kubernetes/pull/112305), [@xing-yang](https://github.com/xing-yang)) [SIG Apps]