- When registering with a 1.17+ API server, a CustomResourceDefinition conversion webhook can now request that only `v1` ConversionReview requests be sent to them. Previously, conversion webhooks were required to support receiving `v1beta1` ConversionReview...

- The `AdmissionReview` API sent to and received from admission webhooks has been promoted to `admission.k8s.io/v1`. Webhooks can specify a preference for receiving `v1` AdmissionReview objects with `admissionReviewVersions: ["v1","v1beta1"]`, and must respond with an API object in the same `apiVersion` they are sent. When webhooks use `admission.k8s.io/v1`, the following additional validation is performed on their responses:...

records that no more values will be sent on the channel.
It is an error if <code>ch</code> is a receive-only channel.
Sending to or closing a closed channel causes a <a href="#Run_time_panics">run-time panic</a>.
Closing the nil channel also causes a <a href="#Run_time_panics">run-time panic</a>.
After calling <code>close</code>, and after any previously
sent values have been received, receive operations will return

a token with the given audience bound to the current pod and its service account. This KSA token along with required annotations on the KSA defined in configuration will be sent to the credential provider plugin via its standard input (along with the image information that is already sent today). The KSA annotations to be sent are configurable in the kubelet credential provider configuration. ([#128372](https://github.com/kubernetes/kubernetes/pull/128372), [@aramase](https://github.com/aramase))...

### Extensibility around core Kubernetes APIs

#### CustomResourceDefinitions Pruning

    * fixed bugs and improved performance in Stackdriver Sink
* fluentd-gcp addon: Fix a bug in the event-exporter, when repeated events were not sent to Stackdriver. ([#50511](https://github.com/kubernetes/kubernetes/pull/50511), [@crassirostris](https://github.com/crassirostris))

- Fixed a kubelet issue that could result in invalid pod status updates to be sent to the api-server where pods would be reported in a terminal phase but also report a ready condition of true in some cases. ([#110479](https://github.com/kubernetes/kubernetes/pull/110479), [@bobbypage](https://github.com/bobbypage)) [SIG Node and...

* Fix panic in kubectl cp command ([#75037](https://github.com/kubernetes/kubernetes/pull/75037), [@soltysh](https://github.com/soltysh))
* Fixes an issue with missing apiVersion/kind in object data sent to admission webhooks ([#74448](https://github.com/kubernetes/kubernetes/pull/74448), [@liggitt](https://github.com/liggitt))

* fix Azure Container Registry anonymous repo image pull error ([#74715](https://github.com/kubernetes/kubernetes/pull/74715), [@andyzhangx](https://github.com/andyzhangx))
* Fixes an issue with missing apiVersion/kind in object data sent to admission webhooks ([#74448](https://github.com/kubernetes/kubernetes/pull/74448), [@liggitt](https://github.com/liggitt))

- Bookmark events are now sent immediately after all items in the watchCache store have been processed, improving consistency in client behavior. ([#127012](https://github.com/kubernetes/kubernetes/pull/127012), [@Chaunceyctx](https://github.com/Chaunceyctx))