resp.flushBuffer();
            return;
        } catch (final DfsReferral dr) {
            StringBuffer redir = req.getRequestURL();
            final String qs = req.getQueryString();
            redir = new StringBuffer(redir.substring(0, redir.length() - req.getPathInfo().length()));
            redir.append('/');
            redir.append(dr.server);

     * @return The login credential or null if processing fails.
     */
    protected LoginCredential processAuthenticationData(final HttpServletRequest request) {
        final StringBuffer urlBuf = request.getRequestURL();
        final String queryStr = request.getQueryString();
        if (queryStr != null) {
            urlBuf.append('?').append(queryStr);
        }