public function hiddenFormFields()
    {
        $fields = $this->getParameter('fields');

        if (empty($fields))
            return '';

        $html_array = ArrayUtils::htmlArrayFlatten($fields);

        foreach ($html_array as $name => $value) {
            $name  = htmlentities($name, ENT_QUOTES);
            $value = htmlentities($value, ENT_QUOTES);

            $output[] = "<input type=\"hidden\" name=\"$name\" value=\"$value\" />";
        }

        return join("\n", $output);
    }