private function registerCache(ContainerBuilder $container): self
    {
        $container->register('contentful.delivery.cache_clearer', CacheClearer::class)
            ->setAbstract(\true)
        ;

        $container->register('contentful.delivery.cache_warmer', CacheWarmer::class)
            ->setAbstract(\true)
        ;

        return $this;
    }