### <a href="https://marshmallow.readthedocs.io/en/3.0/" class="external-link" target="_blank">Marshmallow</a>

APIシステムで必要とされる主な機能の一つに、コード (Python) からデータを取り出して、ネットワークを介して送れるものに変換するデータの「<abbr title="marshalling, conversion">シリアライゼーション</abbr>」があります。例えば、データベースのデータを含むオブジェクトをJSONオブジェクトに変換したり、`datetime` オブジェクトを文字列に変換するなどです。

- 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))

- 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)) [SIG API Machinery]

"+o]||l["* "+o]))for(i in l)if((s=i.split(" "))[1]===o&&(a=l[u+" "+s[0]]||l["* "+s[0]])){!0===a?a=l[i]:!0!==l[i]&&(o=s[0],c.unshift(s[1]));break}if(!0!==a)if(a&&e["throws"])t=a(t);else try{t=a(t)}catch(e){return{state:"parsererror",error:a?e:"No conversion from "+u+" to "+o}}}return{state:"success",data:t}}(v,s,T,i),i?(v.ifModified&&((u=T.getResponseHeader("Last-Modified"))&&(ce.lastModified[f]=u),(u=T.getResponseHeader("etag"))&&(ce.etag[f]=u)),204===e||"HEAD"===v.type?l="nocontent":304===e?l="n...

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

## 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]

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

- 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))

"+f]||j["* "+f],!g)for(e in j)if(h=e.split(" "),h[1]===f&&(g=j[i+" "+h[0]]||j["* "+h[0]])){g===!0?g=j[e]:j[e]!==!0&&(f=h[0],k.unshift(h[1]));break}if(g!==!0)if(g&&a["throws"])b=g(b);else try{b=g(b)}catch(l){return{state:"parsererror",error:g?l:"No conversion from "+i+" to "+f}}}return{state:"success",data:b}}n.extend({active:0,lastModified:{},etag:{},ajaxSettings:{url:fc,type:"GET",isLocal:jc.test(ec[1]),global:!0,processData:!0,async:!0,contentType:"application/x-www-form-urlencoded; charset=UTF-8...

"+o]||l["* "+o]))for(i in l)if((s=i.split(" "))[1]===o&&(a=l[u+" "+s[0]]||l["* "+s[0]])){!0===a?a=l[i]:!0!==l[i]&&(o=s[0],c.unshift(s[1]));break}if(!0!==a)if(a&&e["throws"])t=a(t);else try{t=a(t)}catch(e){return{state:"parsererror",error:a?e:"No conversion from "+u+" to "+o}}}return{state:"success",data:t}}(v,s,T,i),i?(v.ifModified&&((u=T.getResponseHeader("Last-Modified"))&&(ce.lastModified[f]=u),(u=T.getResponseHeader("etag"))&&(ce.etag[f]=u)),204===e||"HEAD"===v.type?l="nocontent":304===e?l="n...