- PersistentVolumeClaim objects are no longer left with storage class...

- Kube-apiserver: fixes scale subresource patch handling to avoid returning unnecessary 409 Conflict error to clients ([#90342](https://github.com/kubernetes/kubernetes/pull/90342), [@liggitt](https://github.com/liggitt)) [SIG Apps, Autoscaling and Testing]

- Kube-aggregator certificates are dynamically loaded on change from disk ([#92791](https://github.com/kubernetes/kubernetes/pull/92791), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery]
- Kube-apiserver: fixed a bug returning inconsistent results from list requests which set a field or label selector and set a paging limit ([#94002](https://github.com/kubernetes/kubernetes/pull/94002), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery]

### Feature

protobuf you will be forced to restore from backup, and you will lose any changes
since you converted to protobuf.  After conversion to protobuf, you should
validate the correct operation of your cluster thoroughly before returning it
to normal operation.

Backups are always a good precaution, particularly around upgrades, but this
upgrade has multiple known issues where the only remedy is to restore from
backup.

   ([#123003](https://github.com/kubernetes/kubernetes/pull/123003), [@alexzielenski](https://github.com/alexzielenski))
- Fixed a non-recursive list returning "resource version too high" error when consistent listing from cache is enabled.
   ([#123674](https://github.com/kubernetes/kubernetes/pull/123674), [@serathius](https://github.com/serathius))

* Filter out non-RestartAlways mirror pod in restart test. ([#37203](https://github.com/kubernetes/kubernetes/pull/37203), [@Random-Liu](https://github.com/Random-Liu))
* Validate volume spec before returning azure mounter ([#37018](https://github.com/kubernetes/kubernetes/pull/37018), [@rootfs](https://github.com/rootfs))

- Added alpha support for `WindowsHostNetworking` feature. ([#112961](https://github.com/kubernetes/kubernetes/pull/112961), [@marosset](https://github.com/marosset))
- Added alpha support for returning container and pod metrics from CRI, instead of cAdvsior. ([#113609](https://github.com/kubernetes/kubernetes/pull/113609), [@haircommander](https://github.com/haircommander))

- Promote ServiceNodePortStaticSubrange to stable and lock to default ([#120233](https://github.com/kubernetes/kubernetes/pull/120233), [@xuzhenglun](https://github.com/xuzhenglun)) [SIG Network]

* Protobuf serialization does not distinguish between `[]` and `null`.
API fields previously capable of storing and returning either `[]` and `null` via JSON API requests (for example, the Endpoints `subsets` field)
can now store only `null` when created using the protobuf content-type or stored in etcd using protobuf serialization (the default in 1.6).