Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/k8s.io/client-go/tools/reference/ref.go

@@ -0,0 +1,126 @@
+/*
+Copyright 2014 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 reference
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+
+	"k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+var (
+	// Errors that could be returned by GetReference.
+	ErrNilObject  = errors.New("can't reference a nil object")
+	ErrNoSelfLink = errors.New("selfLink was empty, can't make reference")
+)
+
+// GetReference returns an ObjectReference which refers to the given
+// object, or an error if the object doesn't follow the conventions
+// that would allow this.
+// TODO: should take a meta.Interface see http://issue.k8s.io/7127
+func GetReference(scheme *runtime.Scheme, obj runtime.Object) (*v1.ObjectReference, error) {
+	if obj == nil {
+		return nil, ErrNilObject
+	}
+	if ref, ok := obj.(*v1.ObjectReference); ok {
+		// Don't make a reference to a reference.
+		return ref, nil
+	}
+
+	gvk := obj.GetObjectKind().GroupVersionKind()
+
+	// if the object referenced is actually persisted, we can just get kind from meta
+	// if we are building an object reference to something not yet persisted, we should fallback to scheme
+	kind := gvk.Kind
+	if len(kind) == 0 {
+		// TODO: this is wrong
+		gvks, _, err := scheme.ObjectKinds(obj)
+		if err != nil {
+			return nil, err
+		}
+		kind = gvks[0].Kind
+	}
+
+	// An object that implements only List has enough metadata to build a reference
+	var listMeta metav1.Common
+	objectMeta, err := meta.Accessor(obj)
+	if err != nil {
+		listMeta, err = meta.CommonAccessor(obj)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		listMeta = objectMeta
+	}
+
+	// if the object referenced is actually persisted, we can also get version from meta
+	version := gvk.GroupVersion().String()
+	if len(version) == 0 {
+		selfLink := listMeta.GetSelfLink()
+		if len(selfLink) == 0 {
+			return nil, ErrNoSelfLink
+		}
+		selfLinkUrl, err := url.Parse(selfLink)
+		if err != nil {
+			return nil, err
+		}
+		// example paths: /<prefix>/<version>/*
+		parts := strings.Split(selfLinkUrl.Path, "/")
+		if len(parts) < 4 {
+			return nil, fmt.Errorf("unexpected self link format: '%v'; got version '%v'", selfLink, version)
+		}
+		if parts[1] == "api" {
+			version = parts[2]
+		} else {
+			version = parts[2] + "/" + parts[3]
+		}
+	}
+
+	// only has list metadata
+	if objectMeta == nil {
+		return &v1.ObjectReference{
+			Kind:            kind,
+			APIVersion:      version,
+			ResourceVersion: listMeta.GetResourceVersion(),
+		}, nil
+	}
+
+	return &v1.ObjectReference{
+		Kind:            kind,
+		APIVersion:      version,
+		Name:            objectMeta.GetName(),
+		Namespace:       objectMeta.GetNamespace(),
+		UID:             objectMeta.GetUID(),
+		ResourceVersion: objectMeta.GetResourceVersion(),
+	}, nil
+}
+
+// GetPartialReference is exactly like GetReference, but allows you to set the FieldPath.
+func GetPartialReference(scheme *runtime.Scheme, obj runtime.Object, fieldPath string) (*v1.ObjectReference, error) {
+	ref, err := GetReference(scheme, obj)
+	if err != nil {
+		return nil, err
+	}
+	ref.FieldPath = fieldPath
+	return ref, nil
+}