* Deprecate OpenAPI spec for GroupVersion endpoints in favor of single spec /swagger.json ([#35388](https://github.com/kubernetes/kubernetes/pull/35388), [@mbohlool](https://github.com/mbohlool))
* kubelet authn/authz ([#34381](https://github.com/kubernetes/kubernetes/pull/34381), [@liggitt](https://github.com/liggitt))

  - The /swagger.json and /swagger-2.0.0.pb-v1 schema documents, deprecated since v1.10, have been removed in favor of `/openapi/v2` ([#73148](https://github.com/kubernetes/kubernetes/pull/73148), [@liggitt](https://github.com/liggitt))

* Kubectl: Remove swagger 1.2 validation. Also removes options `--use-openapi` and `--schema-cache-dir` as these are no longer needed. ([#53232](https://github.com/kubernetes/kubernetes/pull/53232), [@apelisse](https://github.com/apelisse))

      - [Cluster federation](#cluster-federation-1)
      - [Credential provider](#credential-provider)
      - [Information for Kubernetes clients (openapi, swagger, client-go)](#information-for-kubernetes-clients-openapi-swagger-client-go)
      - [Instrumentation](#instrumentation-1)
      - [Internal storage layer](#internal-storage-layer)
      - [Kubernetes Dashboard](#kubernetes-dashboard)

  If set to an empty string, caching is disabled.

- Kubectl now performs validation against OpenAPI schema instead of Swagger 1.2. If
  OpenAPI is not available on the server, it falls back to the old Swagger 1.2.

- Added Italian translation for kubectl.

- Added German translation for kubectl.

#### Scheduling

<table>
  <tr>
    <td>previous</td>
    <td>now</td>
  </tr>
  <tr>
    <td>GET /swagger.json</td>
    <td>GET /openapi/v2

  is beta but disabled by default. ([#120198](https://github.com/kubernetes/kubernetes/pull/120198), [@pacoxu](https://github.com/pacoxu))
- `kubectl` will not support the `/swagger-2.0.0.pb-v1` endpoint that has been long deprecated. ([#119410](https://github.com/kubernetes/kubernetes/pull/119410), [@Jefftree](https://github.com/Jefftree))

* genericapiserver: turn APIContainer.SecretRoutes into a real ServeMux ([#38826](https://github.com/kubernetes/kubernetes/pull/38826), [@sttts](https://github.com/sttts))
* genericapiserver: unify swagger and openapi in config ([#38690](https://github.com/kubernetes/kubernetes/pull/38690), [@sttts](https://github.com/sttts))

### Client

	"fmt"
	"hash"
	"io"
)

// Tagger is the interface that wraps the basic ETag method.
type Tagger interface {
	ETag() ETag
}

type wrapReader struct {
	io.Reader
	Tagger
}

var _ Tagger = wrapReader{} // compiler check

// ETag returns the ETag of the underlying Tagger.
func (r wrapReader) ETag() ETag {
	if r.Tagger == nil {
		return nil
	}
	return r.Tagger.ETag()
}

func (r *Reader) ActualSize() int64 { return r.actualSize }

// ETag returns the ETag computed by an underlying etag.Tagger.
// If the underlying io.Reader does not implement etag.Tagger
// it returns nil.
func (r *Reader) ETag() etag.ETag {
	if t, ok := r.src.(etag.Tagger); ok {
		return t.ETag()
	}
	return nil
}

// MD5Current returns the MD5 checksum of the content