1. update clientset, deepcopy using code-generator

2. add a dummy file tools.go to force "go mod vendor" to see
code-generator as dependencies
3. add a script to update CRD
4. add a README to document CRD updating steps
run go mod tidy
update README

vendor/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured/helpers.go

@@ -27,11 +27,15 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/json"
+	"k8s.io/klog"
 )
 
 // NestedFieldCopy returns a deep copy of the value of a nested field.
 // Returns false if the value is missing.
 // No error is returned for a nil field.
+//
+// Note: fields passed to this function are treated as keys within the passed
+// object; no array/slice syntax is supported.
 func NestedFieldCopy(obj map[string]interface{}, fields ...string) (interface{}, bool, error) {
 	val, found, err := NestedFieldNoCopy(obj, fields...)
 	if !found || err != nil {
@@ -43,6 +47,9 @@ func NestedFieldCopy(obj map[string]interface{}, fields ...string) (interface{},
 // NestedFieldNoCopy returns a reference to a nested field.
 // Returns false if value is not found and an error if unable
 // to traverse obj.
+//
+// Note: fields passed to this function are treated as keys within the passed
+// object; no array/slice syntax is supported.
 func NestedFieldNoCopy(obj map[string]interface{}, fields ...string) (interface{}, bool, error) {
 	var val interface{} = obj
 
@@ -323,6 +330,8 @@ var UnstructuredJSONScheme runtime.Codec = unstructuredJSONScheme{}
 
 type unstructuredJSONScheme struct{}
 
+const unstructuredJSONSchemeIdentifier runtime.Identifier = "unstructuredJSON"
+
 func (s unstructuredJSONScheme) Decode(data []byte, _ *schema.GroupVersionKind, obj runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) {
 	var err error
 	if obj != nil {
@@ -343,7 +352,14 @@ func (s unstructuredJSONScheme) Decode(data []byte, _ *schema.GroupVersionKind,
 	return obj, &gvk, nil
 }
 
-func (unstructuredJSONScheme) Encode(obj runtime.Object, w io.Writer) error {
+func (s unstructuredJSONScheme) Encode(obj runtime.Object, w io.Writer) error {
+	if co, ok := obj.(runtime.CacheableObject); ok {
+		return co.CacheEncode(s.Identifier(), s.doEncode, w)
+	}
+	return s.doEncode(obj, w)
+}
+
+func (unstructuredJSONScheme) doEncode(obj runtime.Object, w io.Writer) error {
 	switch t := obj.(type) {
 	case *Unstructured:
 		return json.NewEncoder(w).Encode(t.Object)
@@ -367,6 +383,11 @@ func (unstructuredJSONScheme) Encode(obj runtime.Object, w io.Writer) error {
 	}
 }
 
+// Identifier implements runtime.Encoder interface.
+func (unstructuredJSONScheme) Identifier() runtime.Identifier {
+	return unstructuredJSONSchemeIdentifier
+}
+
 func (s unstructuredJSONScheme) decode(data []byte) (runtime.Object, error) {
 	type detector struct {
 		Items gojson.RawMessage
@@ -394,12 +415,6 @@ func (s unstructuredJSONScheme) decodeInto(data []byte, obj runtime.Object) erro
 		return s.decodeToUnstructured(data, x)
 	case *UnstructuredList:
 		return s.decodeToList(data, x)
-	case *runtime.VersionedObjects:
-		o, err := s.decode(data)
-		if err == nil {
-			x.Objects = []runtime.Object{o}
-		}
-		return err
 	default:
 		return json.Unmarshal(data, x)
 	}
@@ -454,12 +469,30 @@ func (s unstructuredJSONScheme) decodeToList(data []byte, list *UnstructuredList
 	return nil
 }
 
-type JSONFallbackEncoder struct {
-	runtime.Encoder
+type jsonFallbackEncoder struct {
+	encoder    runtime.Encoder
+	identifier runtime.Identifier
 }
 
-func (c JSONFallbackEncoder) Encode(obj runtime.Object, w io.Writer) error {
-	err := c.Encoder.Encode(obj, w)
+func NewJSONFallbackEncoder(encoder runtime.Encoder) runtime.Encoder {
+	result := map[string]string{
+		"name": "fallback",
+		"base": string(encoder.Identifier()),
+	}
+	identifier, err := gojson.Marshal(result)
+	if err != nil {
+		klog.Fatalf("Failed marshaling identifier for jsonFallbackEncoder: %v", err)
+	}
+	return &jsonFallbackEncoder{
+		encoder:    encoder,
+		identifier: runtime.Identifier(identifier),
+	}
+}
+
+func (c *jsonFallbackEncoder) Encode(obj runtime.Object, w io.Writer) error {
+	// There is no need to handle runtime.CacheableObject, as we only
+	// fallback to other encoders here.
+	err := c.encoder.Encode(obj, w)
 	if runtime.IsNotRegisteredError(err) {
 		switch obj.(type) {
 		case *Unstructured, *UnstructuredList:
@@ -468,3 +501,8 @@ func (c JSONFallbackEncoder) Encode(obj runtime.Object, w io.Writer) error {
 	}
 	return err
 }
+
+// Identifier implements runtime.Encoder interface.
+func (c *jsonFallbackEncoder) Identifier() runtime.Identifier {
+	return c.identifier
+}