Update/verify client generator in scripts

cmd/libs/go2idl/args/args.go

@@ -37,10 +37,12 @@ import (
 // Default returns a defaulted GeneratorArgs. You may change the defaults
 // before calling AddFlags.
 func Default() *GeneratorArgs {
-	return &GeneratorArgs{
+	generatorArgs := &GeneratorArgs{
 		OutputBase:       DefaultSourceTree(),
 		GoHeaderFilePath: filepath.Join(DefaultSourceTree(), "k8s.io/kubernetes/hack/boilerplate/boilerplate.go.txt"),
 	}
+	generatorArgs.AddFlags(pflag.CommandLine)
+	return generatorArgs
 }
 
 // GeneratorArgs has arguments common to most generators.
@@ -105,7 +107,6 @@ func DefaultSourceTree() string {
 // If you don't need any non-default behavior, use as:
 // args.Default().Execute(...)
 func (g *GeneratorArgs) Execute(nameSystems namer.NameSystems, defaultSystem string, pkgs func(*generator.Context, *GeneratorArgs) generator.Packages) error {
-	g.AddFlags(pflag.CommandLine)
 	pflag.Parse()
 
 	b, err := g.NewBuilder()