Nelmio\SecurityBundle\ContentSecurityPolicy\PolicyManager::getLevel2 PHP Method

    private function getLevel2()
    {
        static $directives = null;
        if (null === $directives) {
            $directives = array_merge($this->getLevel1(), array('base-uri', 'child-src', 'form-action', 'frame-ancestors', 'plugin-types'));
        }
        return $directives;
    }