/**
     * Deletes documents matching the specified search parameters.
     *
     * @param request The HTTP servlet request
     * @param params The search request parameters to identify documents to delete
     * @return Number of documents deleted
     */
    public long deleteByQuery(final HttpServletRequest request, final SearchRequestParams params) {

     *
     * @return The username, or "guest" if not logged in.
     */
    public String getUsername() {
        return getRequestManager().findUserBean(FessUserBean.class).map(FessUserBean::getUserId).orElse(Constants.GUEST_USER);
    }

    /**
     * Gets the request manager.
     *
     * @return The request manager.
     */
    protected RequestManager getRequestManager() {