Simplify some of the plugin testing code.

plugin/builtin/ConfigMapGenerator.go

@@ -1,20 +1,7 @@
 // +build plugin
 
-/*
-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.
-*/
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
 
 //go:generate go run sigs.k8s.io/kustomize/cmd/pluginator
 package main
@@ -27,8 +14,8 @@ import (
 )
 
 type plugin struct {
-	ldr     ifc.Loader
-	rf      *resmap.Factory
+	ldr ifc.Loader
+	rf  *resmap.Factory
 	types.GeneratorOptions
 	types.ConfigMapArgs
 }