diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/unfold.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/unfold.go
new file mode 100644
index 00000000000..d135757ee7b
--- /dev/null
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/unfold.go
@@ -0,0 +1,63 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package schema
+
+// Unfold expands vendor extensions of a structural schema.
+// It mutates the receiver.
+func (s *Structural) Unfold() *Structural {
+	if s == nil {
+		return nil
+	}
+
+	mapper := Visitor{
+		Structural: func(s *Structural) bool {
+			if !s.XIntOrString {
+				return false
+			}
+
+			skipAnyOf := isIntOrStringAnyOfPattern(s)
+			skipFirstAllOfAnyOf := isIntOrStringAllOfPattern(s)
+			if skipAnyOf || skipFirstAllOfAnyOf {
+				return false
+			}
+
+			if s.AnyOf == nil {
+				s.AnyOf = []NestedValueValidation{
+					{ForbiddenGenerics: Generic{Type: "integer"}},
+					{ForbiddenGenerics: Generic{Type: "string"}},
+				}
+			} else {
+				s.AllOf = append([]NestedValueValidation{
+					{
+						ValueValidation: ValueValidation{
+							AnyOf: []NestedValueValidation{
+								{ForbiddenGenerics: Generic{Type: "integer"}},
+								{ForbiddenGenerics: Generic{Type: "string"}},
+							},
+						},
+					},
+				}, s.AllOf...)
+			}
+
+			return true
+		},
+		NestedValueValidation: nil, // x-kubernetes-int-or-string cannot be set in nested value validation
+	}
+	mapper.Visit(s)
+
+	return s
+}
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/validation.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/validation.go
index a6da5b1c899..e864fe8c249 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/validation.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/validation.go
@@ -97,15 +97,8 @@ func validateStructuralInvariants(s *Structural, lvl level, fldPath *field.Path)
 	//      - type: integer
 	//      - type: string
 	//    - ... zero or more
-	skipAnyOf := false
-	skipFirstAllOfAnyOf := false
-	if s.XIntOrString && s.ValueValidation != nil {
-		if len(s.ValueValidation.AnyOf) == 2 && reflect.DeepEqual(s.ValueValidation.AnyOf, intOrStringAnyOf) {
-			skipAnyOf = true
-		} else if len(s.ValueValidation.AllOf) >= 1 && len(s.ValueValidation.AllOf[0].AnyOf) == 2 && reflect.DeepEqual(s.ValueValidation.AllOf[0].AnyOf, intOrStringAnyOf) {
-			skipFirstAllOfAnyOf = true
-		}
-	}
+	skipAnyOf := isIntOrStringAnyOfPattern(s)
+	skipFirstAllOfAnyOf := isIntOrStringAllOfPattern(s)
 
 	allErrs = append(allErrs, validateValueValidation(s.ValueValidation, skipAnyOf, skipFirstAllOfAnyOf, lvl, fldPath)...)
 
@@ -157,6 +150,20 @@ func validateStructuralInvariants(s *Structural, lvl level, fldPath *field.Path)
 	return allErrs
 }
 
+func isIntOrStringAnyOfPattern(s *Structural) bool {
+	if s == nil || s.ValueValidation == nil {
+		return false
+	}
+	return len(s.ValueValidation.AnyOf) == 2 && reflect.DeepEqual(s.ValueValidation.AnyOf, intOrStringAnyOf)
+}
+
+func isIntOrStringAllOfPattern(s *Structural) bool {
+	if s == nil || s.ValueValidation == nil {
+		return false
+	}
+	return len(s.ValueValidation.AllOf) >= 1 && len(s.ValueValidation.AllOf[0].AnyOf) == 2 && reflect.DeepEqual(s.ValueValidation.AllOf[0].AnyOf, intOrStringAnyOf)
+}
+
 // validateGeneric checks the generic fields of a structural schema.
 func validateGeneric(g *Generic, lvl level, fldPath *field.Path) field.ErrorList {
 	if g == nil {