protected function getRoutableNodeClasses()
    {
        $metadata = $this->manager->getClassMetadata(Node::class);
        $routables = array_values(array_filter($metadata->subClasses, function($subNode) {
            $reflection = new \ReflectionClass($subNode);
            return $reflection->implementsInterface(RoutableNodeInterface::class);
        }));

        return $routables;
    }