protected static String normalizeUrl(String url) throws URISyntaxException {
        URI uri = new URI(url);
        String scheme = uri.getScheme().toLowerCase();
        String authority = uri.getAuthority().toLowerCase();
        boolean dropPort = (scheme.equals("http") && uri.getPort() == 80)
                           || (scheme.equals("https") && uri.getPort() == 443);
        if (dropPort) {
            // find the last : in the authority
            int index = authority.lastIndexOf(":");
            if (index >= 0) {
                authority = authority.substring(0, index);
            }
        }
        String path = uri.getRawPath();
        if (path == null || path.length() <= 0) {
            path = "/"; // conforms to RFC 2616 section 3.2.2
        }
        // we know that there is no query and no fragment here.
        return scheme + "://" + authority + path;
    }