private static string CreateQueryString(IEnumerable<KeyValuePair<string, string>> parameters) { var normalized = parameters .GroupBy(p => p.Key) .Select(p => new { p.Key, Value = String.Join("", p.Select(r => r.Value)) }) .ToArray(); return String.Join("&", normalized.Select(p => p.Key + "=" + Uri.EscapeDataString(p.Value))); }