private function addClassContentDir(Config $config, callable $recipe = null)
    {
        if (null !== $recipe) {
            $this->runRecipe($config, $recipe);
        } else {
            $directory = realpath(dirname($config->getBaseDir()).DIRECTORY_SEPARATOR.'ClassContent');
            if (false !== $directory) {
                $this->application->unshiftClassContentDir($directory);
            }
        }
    }