1. update clientset, deepcopy using code-generator

2. add a dummy file tools.go to force "go mod vendor" to see
code-generator as dependencies
3. add a script to update CRD
4. add a README to document CRD updating steps
run go mod tidy
update README

pkg/apis/volumesnapshot/v1beta1/zz_generated.deepcopy.go

@@ -2,10 +2,13 @@
 
 /*
 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.
@@ -13,12 +16,12 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// Code generated by controller-gen. DO NOT EDIT.
+// Code generated by deepcopy-gen. DO NOT EDIT.
 
 package v1beta1
 
 import (
-	"k8s.io/apimachinery/pkg/runtime"
+	runtime "k8s.io/apimachinery/pkg/runtime"
 )
 
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
@@ -32,6 +35,7 @@ func (in *VolumeSnapshot) DeepCopyInto(out *VolumeSnapshot) {
 		*out = new(VolumeSnapshotStatus)
 		(*in).DeepCopyInto(*out)
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshot.
@@ -64,6 +68,7 @@ func (in *VolumeSnapshotClass) DeepCopyInto(out *VolumeSnapshotClass) {
 			(*out)[key] = val
 		}
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotClass.
@@ -96,6 +101,7 @@ func (in *VolumeSnapshotClassList) DeepCopyInto(out *VolumeSnapshotClassList) {
 			(*in)[i].DeepCopyInto(&(*out)[i])
 		}
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotClassList.
@@ -127,6 +133,7 @@ func (in *VolumeSnapshotContent) DeepCopyInto(out *VolumeSnapshotContent) {
 		*out = new(VolumeSnapshotContentStatus)
 		(*in).DeepCopyInto(*out)
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotContent.
@@ -159,6 +166,7 @@ func (in *VolumeSnapshotContentList) DeepCopyInto(out *VolumeSnapshotContentList
 			(*in)[i].DeepCopyInto(&(*out)[i])
 		}
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotContentList.
@@ -192,6 +200,7 @@ func (in *VolumeSnapshotContentSource) DeepCopyInto(out *VolumeSnapshotContentSo
 		*out = new(string)
 		**out = **in
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotContentSource.
@@ -214,6 +223,7 @@ func (in *VolumeSnapshotContentSpec) DeepCopyInto(out *VolumeSnapshotContentSpec
 		**out = **in
 	}
 	in.Source.DeepCopyInto(&out.Source)
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotContentSpec.
@@ -254,6 +264,7 @@ func (in *VolumeSnapshotContentStatus) DeepCopyInto(out *VolumeSnapshotContentSt
 		*out = new(VolumeSnapshotError)
 		(*in).DeepCopyInto(*out)
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotContentStatus.
@@ -278,6 +289,7 @@ func (in *VolumeSnapshotError) DeepCopyInto(out *VolumeSnapshotError) {
 		*out = new(string)
 		**out = **in
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotError.
@@ -302,6 +314,7 @@ func (in *VolumeSnapshotList) DeepCopyInto(out *VolumeSnapshotList) {
 			(*in)[i].DeepCopyInto(&(*out)[i])
 		}
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotList.
@@ -335,6 +348,7 @@ func (in *VolumeSnapshotSource) DeepCopyInto(out *VolumeSnapshotSource) {
 		*out = new(string)
 		**out = **in
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotSource.
@@ -356,6 +370,7 @@ func (in *VolumeSnapshotSpec) DeepCopyInto(out *VolumeSnapshotSpec) {
 		*out = new(string)
 		**out = **in
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotSpec.
@@ -395,6 +410,7 @@ func (in *VolumeSnapshotStatus) DeepCopyInto(out *VolumeSnapshotStatus) {
 		*out = new(VolumeSnapshotError)
 		(*in).DeepCopyInto(*out)
 	}
+	return
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new VolumeSnapshotStatus.