* New conformance tests added for the Garbage Collector ([#60116](https://github.com/kubernetes/kubernetes/pull/60116), [@jennybuckley](https://github.com/jennybuckley))

* Fixes a bug where character devices are not recognized by the kubelet ([#60440](https://github.com/kubernetes/kubernetes/pull/60440), [@andrewsykim](https://github.com/andrewsykim))

* Support new NODE_OS_DISTRIBUTION 'custom' on GCE ([#61235](https://github.com/kubernetes/kubernetes/pull/61235), [@yguo0905](https://github.com/yguo0905))
* Fixes a bug where character devices are not recognized by the kubelet ([#60440](https://github.com/kubernetes/kubernetes/pull/60440), [@andrewsykim](https://github.com/andrewsykim))

- Kube-apiserver: multiple comma-separated protocols in a single X-Stream-Protocol-Version header are now recognized, in addition to multiple headers, complying with RFC2616 ([#89857](https://github.com/kubernetes/kubernetes/pull/89857), [@tedyu](https://github.com/tedyu)) [SIG API Machinery]

* PodSecurityPolicy now recognizes pods that specify `runAsNonRoot: false` in their security context and does not overwrite the specified value ([#47073](https://github.com/kubernetes/kubernetes/pull/47073), [@Q-Lee](https://github.com/Q-Lee))

- kubeadm commands now print warnings if input YAML documents contain unknown or duplicate fields.
- kubeadm now properly recognizes Docker 18.09.0 and newer, but still treats 18.06 as the default supported version.
- kubeadm now automatically sets the `--pod-infra-container-image` flag when starting the kubelet.

### SIG IBM Cloud

- Fixes a bug that non directory hostpath type can be recognized as HostPathFile and adds e2e tests for HostPathType ([#64829](https://github.com/kubernetes/kubernetes/pull/64829), [@dixudx](https://github.com/dixudx)) [SIG Apps, Storage and Testing]

- The kubelet recognizes the --containerd-namespace flag to configure the namespace used by cadvisor. ([#87054](https://github.com/kubernetes/kubernetes/pull/87054), [@changyaowei](https://github.com/changyaowei)) [SIG Node]

- Printed `SizeLimit` of `EmptyDir` in `kubectl describe pod` outputs. ([#69279](https://github.com/kubernetes/kubernetes/pull/69279), [@dtaniwaki](https://github.com/dtaniwaki))
- `kubectl delete --all-namespaces` is now a recognized flag. ([#73716](https://github.com/kubernetes/kubernetes/pull/73716), [@deads2k](https://github.com/deads2k))

### Cloud Provider

- `kubectl prune v2`: Switched annotation from `contains-group-resources` to `contains-group-kinds`,
  because this is what we defined in the KEP and is clearer to end-users. Although the functionality is
  in `alpha`, we will recognize the prior annotation. This migration support will be removed in `beta`/`GA`. ([#118942](https://github.com/kubernetes/kubernetes/pull/118942), [@justinsb](https://github.com/justinsb))

  * PodSecurityPolicy now recognizes pods that specify runAsNonRoot: false in their security context and does not overwrite the specified value ([#47073](https://github.com/kubernetes/kubernetes/pull/47073), [@Q-Lee](https://github.com/Q-Lee))