public function fixIfNoneMatchHeader(EventInterface $event) {
        $request = $event->getRequest();
        $ifNoneMatch = $request->headers->get('if-none-match', false);

        if ($ifNoneMatch && strlen($ifNoneMatch) > 34) {
            // Remote quotes
            $ifNoneMatch = trim($ifNoneMatch, '"');

            // Remove everything beyond char 32, that has possibly been added by web servers, and
            // set the header
            $request->headers->set('if-none-match', '"' . substr($ifNoneMatch, 0, 32) . '"');
        }
    }