private function validateCustomTagsConfiguration(
        ContainerInterface $container,
        array $enabledCustomTags
    ) {
        $definedCustomTags = array_keys(
            $container->getParameter(EzPublishCoreExtension::RICHTEXT_CUSTOM_TAGS_PARAMETER)
        );
        foreach ($enabledCustomTags as $customTagName) {
            if (!in_array($customTagName, $definedCustomTags)) {
                throw new InvalidConfigurationException(
                    "Unknown RichText Custom Tag '{$customTagName}'"
                );
            }
        }
    }