Merge pull request #59293 from roycaihw/openapi_endpoint

Automatic merge from submit-queue (batch tested with PRs 60011, 59256, 59293, 60328, 60367). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Serve OpenAPI spec with single /openapi/v2 endpoint

**What this PR does / why we need it**:
We are deprecating format-separated endpoints (`/swagger.json`, `/swagger-2.0.0.json`, `/swagger-2.0.0.pb-v1`, `/swagger-2.0.0.pb-v1.gz`) for OpenAPI spec, and switching to a single `/openapi/v2` endpoint in Kubernetes 1.10. The design doc and deprecation process are tracked at: https://docs.google.com/document/d/19lEqE9lc4yHJ3WJAJxS_G7TcORIJXGHyq3wpwcH28nU

Requested format is specified by setting HTTP headers

header | possible values
-- | --
Accept | `application/json`, `application/com.github.proto-openapi.spec.v2@v1.0+protobuf`
Accept-Encoding | `gzip`

This PR changes dynamic_client (and kubectl as a result) to use the new endpoint. The old endpoints will remain in 1.10 and 1.11, and get removed in 1.12.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
action required: Deprecate format-separated endpoints for OpenAPI spec. Please use single `/openapi/v2` endpoint instead.
```

/sig api-machinery

Kubernetes-commit: d6153194d929ad6c036d5bbbf67a6f892e75feb5

vendor/k8s.io/code-generator/cmd/conversion-gen/generators/conversion.go

@@ -193,7 +193,6 @@ func Packages(context *generator.Context, arguments *args.GeneratorArgs) generat
 
 	packages := generator.Packages{}
 	header := append([]byte(fmt.Sprintf("// +build !%s\n\n", arguments.GeneratedBuildTag)), boilerplate...)
-	header = append(header, []byte("\n// This file was autogenerated by conversion-gen. Do not edit it manually!\n\n")...)
 
 	// Accumulate pre-existing conversion functions.
 	// TODO: This is too ad-hoc.  We need a better way.

vendor/k8s.io/code-generator/cmd/informer-gen/generators/packages.go

@@ -62,12 +62,6 @@ func DefaultNameSystem() string {
 	return "public"
 }
 
-// generatedBy returns information about the arguments used to invoke
-// lister-gen.
-func generatedBy() string {
-	return fmt.Sprintf("\n// This file was automatically generated by informer-gen\n\n")
-}
-
 // objectMetaForPackage returns the type of ObjectMeta used by package p.
 func objectMetaForPackage(p *types.Package) (*types.Type, bool, error) {
 	generatingForPackage := false
@@ -111,8 +105,6 @@ func Packages(context *generator.Context, arguments *args.GeneratorArgs) generat
 		glog.Fatalf("Failed loading boilerplate: %v", err)
 	}
 
-	boilerplate = append(boilerplate, []byte(generatedBy())...)
-
 	customArgs, ok := arguments.CustomArgs.(*informergenargs.CustomArgs)
 	if !ok {
 		glog.Fatalf("Wrong CustomArgs type: %T", arguments.CustomArgs)

vendor/k8s.io/code-generator/cmd/lister-gen/generators/lister.go

@@ -62,12 +62,6 @@ func DefaultNameSystem() string {
 	return "public"
 }
 
-// generatedBy returns information about the arguments used to invoke
-// lister-gen.
-func generatedBy() string {
-	return fmt.Sprintf("\n// This file was automatically generated by lister-gen\n\n")
-}
-
 // Packages makes the client package definition.
 func Packages(context *generator.Context, arguments *args.GeneratorArgs) generator.Packages {
 	boilerplate, err := arguments.LoadGoBoilerplate()
@@ -75,8 +69,6 @@ func Packages(context *generator.Context, arguments *args.GeneratorArgs) generat
 		glog.Fatalf("Failed loading boilerplate: %v", err)
 	}
 
-	boilerplate = append(boilerplate, []byte(generatedBy())...)
-
 	var packageList generator.Packages
 	for _, inputDir := range arguments.InputDirs {
 		p := context.Universe.Package(inputDir)