add support for exec plugins

pkg/types/errors.go

@@ -0,0 +1,29 @@
+/*
+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.
+*/
+
+package types
+
+import (
+	"fmt"
+)
+
+type NoFieldError struct {
+	Field string
+}
+
+func (e NoFieldError) Error() string {
+	return fmt.Sprintf("no field named '%s'", e.Field)
+}