override unmarshalJSON for supportedfeature to ensure comptability

[LiorLieberman]

I messed up the branch name so disregard it.

What type of PR is this? /kind bug

What this PR does / why we need it:

This change is following an issue with the breaking change we introduced in https://github.com/kubernetes-sigs/gateway-api/pull/3200/. Issue link - https://github.com/istio/istio/issues/53846

I added unitests which hopefully provide enough coverage but happy to add more tests if you have ideas.

Which issue(s) this PR fixes:

Fixes #3464

Does this PR introduce a user-facing change?:

Add backward compatibility for the older version of SupportedFeature

/cc @howardjohn @youngnick @mikemorris @robscott

[LiorLieberman]

/cc @howardjohn @youngnick @robscott @mikemorris

[robscott]

/cherry-pick release-1.2

[k8s-infra-cherrypick-robot]

@robscott: once the present PR merges, I will cherry-pick it on top of release-1.2 in a new PR and assign it to you.

In response to [this](https://github.com/kubernetes-sigs/gateway-api/pull/3454#issuecomment-2486255325): >/cherry-pick release-1.2 Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[howardjohn]

Looks like we need codegen:

diff --git a/apis/v1/zz_generated.deepcopy.go b/apis/v1/zz_generated.deepcopy.go
index 62fb99b0..fe1fb89b 100644
--- a/apis/v1/zz_generated.deepcopy.go
+++ b/apis/v1/zz_generated.deepcopy.go
@@ -1744,3 +1744,18 @@ func (in *SupportedFeature) DeepCopy() *SupportedFeature {
    in.DeepCopyInto(out)
    return out
 }
+
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *SupportedFeatureInternal) DeepCopyInto(out *SupportedFeatureInternal) {
+   *out = *in
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new SupportedFeatureInternal.
+func (in *SupportedFeatureInternal) DeepCopy() *SupportedFeatureInternal {
+   if in == nil {
+       return nil
+   }
+   out := new(SupportedFeatureInternal)
+   in.DeepCopyInto(out)
+   return out
+}
diff --git a/pkg/generated/openapi/zz_generated.openapi.go b/pkg/generated/openapi/zz_generated.openapi.go
index a613f40a..ca69f4d3 100644
--- a/pkg/generated/openapi/zz_generated.openapi.go
+++ b/pkg/generated/openapi/zz_generated.openapi.go
@@ -145,6 +145,7 @@ func GetOpenAPIDefinitions(ref common.ReferenceCallback) map[string]common.OpenA
        "sigs.k8s.io/gateway-api/apis/v1.SecretObjectReference":                           schema_sigsk8sio_gateway_api_apis_v1_SecretObjectReference(ref),
        "sigs.k8s.io/gateway-api/apis/v1.SessionPersistence":                              schema_sigsk8sio_gateway_api_apis_v1_SessionPersistence(ref),
        "sigs.k8s.io/gateway-api/apis/v1.SupportedFeature":                                schema_sigsk8sio_gateway_api_apis_v1_SupportedFeature(ref),
+       "sigs.k8s.io/gateway-api/apis/v1.SupportedFeatureInternal":                        schema_sigsk8sio_gateway_api_apis_v1_SupportedFeatureInternal(ref),
        "sigs.k8s.io/gateway-api/apis/v1alpha2.BackendLBPolicy":                           schema_sigsk8sio_gateway_api_apis_v1alpha2_BackendLBPolicy(ref),
        "sigs.k8s.io/gateway-api/apis/v1alpha2.BackendLBPolicyList":                       schema_sigsk8sio_gateway_api_apis_v1alpha2_BackendLBPolicyList(ref),
        "sigs.k8s.io/gateway-api/apis/v1alpha2.BackendLBPolicySpec":                       schema_sigsk8sio_gateway_api_apis_v1alpha2_BackendLBPolicySpec(ref),
@@ -3797,8 +3798,7 @@ func schema_sigsk8sio_gateway_api_apis_v1_GatewayClassStatus(ref common.Referenc
                            Items: &spec.SchemaOrArray{
                                Schema: &spec.Schema{
                                    SchemaProps: spec.SchemaProps{
-                                       Default: map[string]interface{}{},
-                                       Ref:     ref("sigs.k8s.io/gateway-api/apis/v1.SupportedFeature"),
+                                       Ref: ref("sigs.k8s.io/gateway-api/apis/v1.SupportedFeature"),
                                    },
                                },
                            },
@@ -5650,6 +5650,27 @@ func schema_sigsk8sio_gateway_api_apis_v1_SupportedFeature(ref common.ReferenceC
    }
 }

+func schema_sigsk8sio_gateway_api_apis_v1_SupportedFeatureInternal(ref common.ReferenceCallback) common.OpenAPIDefinition {
+   return common.OpenAPIDefinition{
+       Schema: spec.Schema{
+           SchemaProps: spec.SchemaProps{
+               Description: "This is solely for the purpose of ensuring backward compatibility and SHOULD NOT be used elsewhere.",
+               Type:        []string{"object"},
+               Properties: map[string]spec.Schema{
+                   "name": {
+                       SchemaProps: spec.SchemaProps{
+                           Default: "",
+                           Type:    []string{"string"},
+                           Format:  "",
+                       },
+                   },
+               },
+               Required: []string{"name"},
+           },
+       },
+   }
+}
+
 func schema_sigsk8sio_gateway_api_apis_v1alpha2_BackendLBPolicy(ref common.ReferenceCallback) common.OpenAPIDefinition {
    return common.OpenAPIDefinition{
        Schema: spec.Schema{

We can do a followup release if needed, but fwiw we are targeting an Istio release tomorrow afternoon that would be great to include this in. Not a big deal if we miss it, though.

[LiorLieberman]

@howardjohn Will ask for approval in the slack chat later today, wdyt about my comment https://github.com/kubernetes-sigs/gateway-api/pull/3454#discussion_r1845242178 ?

[howardjohn]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: LiorLieberman, robscott

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-sigs/gateway-api/blob/main/OWNERS)~~ [robscott] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[k8s-infra-cherrypick-robot]

@robscott: new pull request created: #3465

In response to [this](https://github.com/kubernetes-sigs/gateway-api/pull/3454#issuecomment-2486255325): >/cherry-pick release-1.2 Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.