func (g *generator) getArgNames(m *model.Method, in bool) []string {
	var params []*model.Parameter

	forbidden := map[string]bool{}
	for _, v := range g.packageMap {
		forbidden[v] = true
	}

	if in {
		params = m.In
	} else {
		params = m.Out
	}
	argNames := make([]string, len(params))
	for i, p := range params {
		argNames[i] = sanitizeName(p.Name, forbidden, i)
	}
	if m.Variadic != nil && in {
		name := sanitizeName(m.Variadic.Name, forbidden, len(params))
		argNames = append(argNames, name)
	}
	return argNames
}

...

func sanitizeName(name string, forbidden map[string]bool, i int) string {
	if name == "" || name == "_" || forbidden[name] {
		return fmt.Sprintf("arg%d", i)
	}
	return name
}