public function getRootName(): string
    {
        $className = \get_class($this);
        if ('Bundle\\DependencyInjection\\Configuration' !== mb_substr($className, -40)) {
            throw new BadMethodCallException('This extension does not follow the naming convention; you must overwrite the getRootName() method.');
        }
        $classBaseName = mb_substr($className, 0, mb_strlen($className) - 40);

        return mb_strtolower(str_replace('\\', '_', $classBaseName));
    }