* SearchRequestType.JSON and the role filter mechanism, ensuring
     * users only see documents they are authorized to access.
     * <p>
     * This is the primary extension point for subclasses to customize search behavior.
     *
     * @param query the search query
     * @param fields the field filters (e.g., label)
     * @param extraQueries the extra query filters (e.g., filetype, timestamp)