etcd (v3) store: implements KV methods of storage.Interface

This implements Get(), Create(), Delete(), GetToList(),
List(), GuaranteedUpdate().

pkg/runtime/helper.go

@@ -169,3 +169,13 @@ func (m MultiObjectTyper) IsUnversioned(obj Object) (bool, bool) {
 	}
 	return false, false
 }
+
+// SetZeroValue would set the object of objPtr to zero value of its type.
+func SetZeroValue(objPtr Object) error {
+	v, err := conversion.EnforcePtr(objPtr)
+	if err != nil {
+		return err
+	}
+	v.Set(reflect.Zero(v.Type()))
+	return nil
+}