* Plugins

      * Introduces the ability to extend kubectl by adding third-party plugins. Developer preview, please refer to the documentation for instructions about how to use it. ([#37499](https://github.com/kubernetes/kubernetes/pull/37499), [@fabianofranz](https://github.com/fabianofranz))

Pruning is activated by setting `spec.preserveUnknownFields: false` in the CustomResourceDefinition. A future apiextensions.k8s.io/v1 variant of CRDs will enforce pruning.

content type of `text/plain` containing JSON data would be accepted and the JSON data would be extracted.

But requests with content type `text/plain` are exempt from [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) preflights, for being considered [Simple requests](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests). So, the browser would execute them right away including cookies, and the text content could be a JSON string that would be parsed and accepted...

### SIG Windows development tools

  // +optional
  optional AWSElasticBlockStoreVolumeSource awsElasticBlockStore = 2;

  // hostPath represents a directory on the host.
  // Provisioned by a developer or tester.
  // This is useful for single-node development and testing only!
  // On-host storage is not supported in any way and WILL NOT WORK in a multi-node cluster.

* kubeadm: Enable kubelet client certificate rotation ([#52196](https://github.com/kubernetes/kubernetes/pull/52196), [@luxas](https://github.com/luxas))
* Scheduler predicate developer should respect equivalence class cache ([#52146](https://github.com/kubernetes/kubernetes/pull/52146), [@resouer](https://github.com/resouer))

### API-machinery

### Other (Cleanup or Flake)

- Service session affinity timeout tests are no longer required for Kubernetes network plugin conformance due to variations in existing implementations. New conformance tests will be developed to better express conformance in future releases. ([#112806](https://github.com/kubernetes/kubernetes/pull/112806), [@dcbw](https://github.com/dcbw)) [SIG Architecture, Network and Testing]

## Dependencies

### Added

- Service session affinity timeout tests are no longer required for Kubernetes network plugin conformance due to variations in existing implementations. New conformance tests will be developed to better express conformance in future releases. ([#112806](https://github.com/kubernetes/kubernetes/pull/112806), [@dcbw](https://github.com/dcbw)) [SIG Architecture, Network and Testing]

## Changelog since v1.27.0

## Urgent Upgrade Notes 

### (No, really, you MUST read this before you upgrade)

- Action required for the custom scheduler plugin developers. 
  Here's the breaking change in `EnqueueExtension` in the scheduling framework.