add v1alpha2 registry based conversion (#1006)

* add v1alpha2 registry based conversion

* test defaults, set our 1st explicit default

* fix typos and dates

* move pluginregistry to its own dir

* remove unused v1alpha2.Namespace type

* move migration code folders, remove switch

* validate internalPolicy a single time

* remove structured logs

* simplify return

* check for nil methods

* properly check before adding default evictor

* add TODO comment

* bump copyright year

pkg/framework/plugins/defaultevictor/validation.go

@@ -0,0 +1,30 @@
+/*
+Copyright 2022 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 defaultevictor
+
+import (
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+func ValidateDefaultEvictorArgs(obj runtime.Object) error {
+	args := obj.(*DefaultEvictorArgs)
+
+	if args.PriorityThreshold != nil && len(args.PriorityThreshold.Name) > 0 {
+		return fmt.Errorf("priority threshold misconfigured, only one of priorityThreshold fields can be set, got %v", args)
+	}
+
+	return nil
+}