Sort query string and remove the empty ones

gistfile1.cs

    private static string SanitizeUrl(string url)
    {
        var uri = new Uri(url);
        var path = uri.GetLeftPart(UriPartial.Path);
        path += path.EndsWith("/") ? "" : "/";
        var query = uri.ParseQueryString();
        var dict = new SortedDictionary<string, string>(query.AllKeys
            .Where(k => !string.IsNullOrWhiteSpace(query[k]))
            .ToDictionary(k => k, k => query[k]));
        return (path + ToQueryString(dict)).ToLower();
    }

    private static string ToQueryString(SortedDictionary<string, string> dict)
    {
        var items = new List<string>();
        foreach (var entry in dict)
        {
            items.Add(string.Concat(entry.Key, "=", Uri.EscapeUriString(entry.Value)));
        }
        return (items.Count > 0 ? "?" : "") + string.Join("&", items.ToArray());
    }