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/api/authorization/v1/zz_generated.deepcopy.go

@@ -16,7 +16,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// This file was autogenerated by deepcopy-gen. Do not edit it manually!
+// Code generated by deepcopy-gen. DO NOT EDIT.
 
 package v1
 
@@ -24,6 +24,26 @@ import (
 	runtime "k8s.io/apimachinery/pkg/runtime"
 )
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in ExtraValue) DeepCopyInto(out *ExtraValue) {
+	{
+		in := &in
+		*out = make(ExtraValue, len(*in))
+		copy(*out, *in)
+		return
+	}
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new ExtraValue.
+func (in ExtraValue) DeepCopy() ExtraValue {
+	if in == nil {
+		return nil
+	}
+	out := new(ExtraValue)
+	in.DeepCopyInto(out)
+	return *out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *LocalSubjectAccessReview) DeepCopyInto(out *LocalSubjectAccessReview) {
 	*out = *in
@@ -48,9 +68,8 @@ func (in *LocalSubjectAccessReview) DeepCopy() *LocalSubjectAccessReview {
 func (in *LocalSubjectAccessReview) DeepCopyObject() runtime.Object {
 	if c := in.DeepCopy(); c != nil {
 		return c
-	} else {
-		return nil
 	}
+	return nil
 }
 
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
@@ -171,9 +190,8 @@ func (in *SelfSubjectAccessReview) DeepCopy() *SelfSubjectAccessReview {
 func (in *SelfSubjectAccessReview) DeepCopyObject() runtime.Object {
 	if c := in.DeepCopy(); c != nil {
 		return c
-	} else {
-		return nil
 	}
+	return nil
 }
 
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
@@ -234,9 +252,8 @@ func (in *SelfSubjectRulesReview) DeepCopy() *SelfSubjectRulesReview {
 func (in *SelfSubjectRulesReview) DeepCopyObject() runtime.Object {
 	if c := in.DeepCopy(); c != nil {
 		return c
-	} else {
-		return nil
 	}
+	return nil
 }
 
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
@@ -279,9 +296,8 @@ func (in *SubjectAccessReview) DeepCopy() *SubjectAccessReview {
 func (in *SubjectAccessReview) DeepCopyObject() runtime.Object {
 	if c := in.DeepCopy(); c != nil {
 		return c
-	} else {
-		return nil
 	}
+	return nil
 }
 
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
@@ -314,8 +330,12 @@ func (in *SubjectAccessReviewSpec) DeepCopyInto(out *SubjectAccessReviewSpec) {
 		in, out := &in.Extra, &out.Extra
 		*out = make(map[string]ExtraValue, len(*in))
 		for key, val := range *in {
-			(*out)[key] = make(ExtraValue, len(val))
-			copy((*out)[key], val)
+			if val == nil {
+				(*out)[key] = nil
+			} else {
+				(*out)[key] = make([]string, len(val))
+				copy((*out)[key], val)
+			}
 		}
 	}
 	return