added warning message for deprecated flag (#193)

* added warning message for deprecated flag

* updated markdeprecated

pkg/plugins/helm/v1/api.go

@@ -119,6 +119,7 @@ func (p *createAPISubcommand) BindFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&p.options.chartOptions.Version, helmChartVersionFlag, "", "helm chart version (default: latest)")
 
 	fs.StringVar(&p.options.CRDVersion, crdVersionFlag, defaultCrdVersion, "crd version to generate")
+	_ = fs.MarkDeprecated(crdVersionFlag, util.WarnMessageRemovalV1beta1)
 }
 
 func (p *createAPISubcommand) InjectConfig(c config.Config) error {

pkg/plugins/util/message.go

@@ -0,0 +1,20 @@
+// Copyright 2020 The Operator-SDK 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 util
+
+const WarnMessageRemovalV1beta1 = "The v1beta1 API version for CRDs and Webhooks is deprecated and is no longer offered since " +
+	"Kubernetes 1.22. This flag will be removed in a future release. We " +
+	"recommend that you no longer use the v1beta1 API version" +
+	"More info: https://kubernetes.io/docs/reference/using-api/deprecation-guide/#v1-22"