private function checkDownloads()
    {
        // If images are to be shown, get out.
        if ($this->getShowImages()) {
            return;
        }
        if (($file = Input::get('file')) && ($key = Input::get('fileKey'))) {
            // Check key and return 403 if mismatch.
            if (!(array_key_exists($file, $_SESSION['metaModels_downloads'])
                && $_SESSION['metaModels_downloads'][$file] === $key)) {
                $objHandler = new $GLOBALS['TL_PTY']['error_403']();
                /** @var PageError403 $objHandler */
                $objHandler->generate($file);
            }
            // Send the file to the browser if check succeeded.
            Controller::sendFileToBrowser($file);
        }
    }