- Fixed a regression in `1.27.0` that resulted in `missing metadata in converted object` errors when modifying objects for multi-version custom resource definitions with a conversion strategy of `None`. ([#117301](https://github.com/kubernetes/kubernetes/pull/117301), [@ncdc](https://github.com/ncdc))

In addition, users can now create multiple versions of CustomResourceDefinitions, but without any kind of automatic conversion, and CustomResourceDefinitions now allow specification of additional columns for `kubectl get` output via the `spec.additionalPrinterColumns` field.

### SIG Auth

does not support protobuf encoding, if you roll back to 1.5 after upgrading to
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

- Timeouts set in ListOptions for clients are also be respected locally ([#70998](https://github.com/kubernetes/kubernetes/pull/70998), [@deads2k](https://github.com/deads2k))
- Added support for CRD conversion webhook ([#67006](https://github.com/kubernetes/kubernetes/pull/67006), [@mbohlool](https://github.com/mbohlool))

## Changes by Kind

### Bug or Regression

- Fixes a regression in 1.27.0 that resulted in "missing metadata in converted object" errors when modifying objects for multi-version custom resource definitions with a conversion strategy of `None`. ([#117305](https://github.com/kubernetes/kubernetes/pull/117305), [@ncdc](https://github.com/ncdc)) [SIG API Machinery]

* Fix issue with kubectl annotate when --resource-version is provided. ([#29319](https://github.com/kubernetes/kubernetes/pull/29319), [@juanvallejo](https://github.com/juanvallejo))
* Reverted conversion of influx-db to Pet Set, it is now a Replication Controller. ([#30080](https://github.com/kubernetes/kubernetes/pull/30080), [@jszczepkowski](https://github.com/jszczepkowski))

- Kube-apiserver: Previously persisted `CustomResourceDefinition` objects with an invalid whitespace-only `caBundle` could serve requests that did not require conversion. ([#132514](https://github.com/kubernetes/kubernetes/pull/132514), [@tiffanny29631](https://github.com/tiffanny29631))

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### Feature

- Parallelize calls to conversion webhooks when watching from etcd to prevent watchcache from lagging and helps clusters with slow conversion webhooks or transformers. 

- The `build-tag` flag is reintroduced to conversion-gen and defaulter-gen which allow users to inject custom build tag during code generation process. ([#128259](https://github.com/kubernetes/kubernetes/pull/128259), [@dinhxuanvu](https://github.com/dinhxuanvu))