src/Http/RelayServiceProvider.php
public function getFactory(ContainerInterface $container)
    {
        return new RelayBuilder(function ($middleware) use ($container) {
            return is_string($middleware) ? $container->get($middleware) : $middleware;
        });
    }
public function getFactory(ContainerInterface $container)
    {
        return new RelayBuilder(function ($middleware) use ($container) {
            return is_string($middleware) ? $container->get($middleware) : $middleware;
        });
    }
@param ContainerInterface $container

@return RelayBuilder