prune type in preserve-unknown-fields objects

Signed-off-by: Gautier Delorme <gautier.delorme@gmail.com>

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapi/builder/builder_test.go

@@ -172,8 +172,7 @@ func TestNewBuilder(t *testing.T) {
     },
     "embedded-object": {
       "x-kubernetes-embedded-resource": true,
-      "x-kubernetes-preserve-unknown-fields": true,
-      "type":"object"
+      "x-kubernetes-preserve-unknown-fields": true
     }
   },
   "x-kubernetes-group-version-kind":[{"group":"bar.k8s.io","kind":"Foo","version":"v1"}]

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapi/v2/conversion.go

@@ -81,6 +81,13 @@ func ToStructuralOpenAPIV2(in *structuralschema.Structural) *structuralschema.St
 				changed = true
 			}
 
+			if s.XPreserveUnknownFields && s.Type == "object" {
+				// similar as above, kubectl doesn't properly handle object fields with `x-kubernetes-preserve-unknown-fields: true`
+				s.Type = ""
+
+				changed = true
+			}
+
 			for f, fs := range s.Properties {
 				if fs.Nullable {
 					s.ValueValidation.Required, changed = filterOut(s.ValueValidation.Required, f)

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapi/v2/conversion_test.go

@@ -666,8 +666,7 @@ func Test_ConvertJSONSchemaPropsToOpenAPIv2SchemaByType(t *testing.T) {
 					},
 				},
 			},
-			expected: withVendorExtensions(new(spec.Schema), "x-kubernetes-preserve-unknown-fields", true).
-				Typed("object", ""),
+			expected: withVendorExtensions(new(spec.Schema), "x-kubernetes-preserve-unknown-fields", true),
 		},
 	}