Fix CRD validation error for 'items' field

Signed-off-by: He Xiaoxi <xxhe@alauda.io>

vendor/github.com/go-openapi/spec/ref.go

@@ -15,6 +15,8 @@
 package spec
 
 import (
+	"bytes"
+	"encoding/gob"
 	"encoding/json"
 	"net/http"
 	"os"
@@ -148,6 +150,28 @@ func (r *Ref) UnmarshalJSON(d []byte) error {
 	return r.fromMap(v)
 }
 
+// GobEncode provides a safe gob encoder for Ref
+func (r Ref) GobEncode() ([]byte, error) {
+	var b bytes.Buffer
+	raw, err := r.MarshalJSON()
+	if err != nil {
+		return nil, err
+	}
+	err = gob.NewEncoder(&b).Encode(raw)
+	return b.Bytes(), err
+}
+
+// GobDecode provides a safe gob decoder for Ref
+func (r *Ref) GobDecode(b []byte) error {
+	var raw []byte
+	buf := bytes.NewBuffer(b)
+	err := gob.NewDecoder(buf).Decode(&raw)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(raw, r)
+}
+
 func (r *Ref) fromMap(v map[string]interface{}) error {
 	if v == nil {
 		return nil