protected function checkContainer()
    {
        $container = self::$defaultContainer;
        if (
            null != $this->configPath &&
            file_exists($this->configPath.'/services.php')
        ) {
            $definitions = include $this->configPath.'/services.php';
            $container = (
                new ContainerBuilder(
                    $definitions,
                    true
                )
            )->getContainer();
        }
        return $container;
    }