### Feature

  - 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...

  // +optional
  optional ObjectFieldSelector fieldRef = 1;

  // Selects a resource of the container: only resources limits and requests
  // (limits.cpu, limits.memory, limits.ephemeral-storage, requests.cpu, requests.memory and requests.ephemeral-storage) are currently supported.
  // +optional
  optional ResourceFieldSelector resourceFieldRef = 2;

  // Selects a key of a ConfigMap.

## Changes by Kind

### API Change

- When the kubelet fails to assign CPUs to a Pod because there less available CPUs than the Pod requests, the error message changed from
  `not enough cpus available to satisfy request` to `not enough cpus available to satisfy request: <num_requested> requested, only <num_available> available`. ([#121059](https://github.com/kubernetes/kubernetes/pull/121059), [@matte21](https://github.com/matte21))

* Resolves an issue serving aggregated APIs backed by services that respond to requests to `/` with non-2xx HTTP responses ([#79895](https://...

        * requests for a TLS client certificate for any node are approved if the CSR creator has `create` permission on the `certificatesigningrequests` resource and `nodeclient` subresource in the `certificates.k8s.io` API group

  - apiserver_flowcontrol_dispatch_r: R(the time of the latest request dispatch)
  - apiserver_flowcontrol_latest_s: S(the request last dispatched) = R(when that request starts executing in the virtual world)
  - apiserver_flowcontrol_next_s_bounds: min and max next S among non-empty queues

- Kube-apiserver: fixes a 1.27+ regression in watch stability by serving watch requests without a resourceVersion from the watch cache by default, as in <1.27 (disabling the change in #115096 by default). This mitigates the impact of an etcd watch bug (https://github.com/etcd-io/etcd/pull/17555). If the 1.27 change in #115096 to serve these requests from underlying storage is still desired despite the impact on watch stability, it can be re-enabled with a `Watc...

- If the user specifies an invalid timeout in the request URL, the request will be aborted with an HTTP 400.