Make ServiceBackendPort an atomic struct

This allows different actors to force ownership of it without having to
explicitly unset the other field.

Author: thockin

api/openapi-spec/swagger.json

@@ -799,7 +799,8 @@
             "type": "integer"
           }
         },
-        "type": "object"
+        "type": "object",
+        "x-kubernetes-map-type": "atomic"
       },
       "io.k8s.apimachinery.pkg.apis.meta.v1.APIResource": {
         "description": "APIResource specifies the name of a resource and whether it is namespaced.",

api/openapi-spec/v3/apis__networking.k8s.io__v1_openapi.json

@@ -531,6 +531,7 @@ type IngressServiceBackend struct {
 }
 
 // ServiceBackendPort is the service port being referenced.
+// +structType=atomic
 type ServiceBackendPort struct {
 	// name is the name of the port on the Service.
 	// This is a mutually exclusive setting with "Number".