protected function mergeOldRoutes($version)
{
if (!isset($this->oldRoutes)) {
$this->oldRoutes = $this->router->getRoutes();
}
if (!isset($this->mergedRoutes[$version])) {
$this->mergedRoutes[$version] = $this->routes[$version];
foreach ($this->oldRoutes as $route) {
$this->mergedRoutes[$version]->add($route);
}
}
return $this->mergedRoutes[$version];
}