change cluster schema (#2026)

* change cluster schema

* change cluster schema

vendor/k8s.io/kubectl/pkg/util/openapi/extensions.go

@@ -0,0 +1,27 @@
+/*
+Copyright 2017 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 openapi
+
+import "github.com/go-openapi/spec"
+
+// PrintColumnsKey is the key that defines which columns should be printed
+const PrintColumnsKey = "x-kubernetes-print-columns"
+
+// GetPrintColumns looks for the open API extension for the display columns.
+func GetPrintColumns(extensions spec.Extensions) (string, bool) {
+	return extensions.GetString(PrintColumnsKey)
+}