public HeaderCookieCollection(HeaderCollection headers)
 {
     Headers    = headers;
     _cookies   = new Dictionary <string, HttpCookie>();
     _indexHash = new Dictionary <int, int>();
 }
        public static void FillFromHeaderCollection(this HttpResponseHeaders headers, HeaderCollection targetHeaders)
        {
            if (headers == null)
            {
                throw new ArgumentNullException(nameof(headers));
            }
            if (targetHeaders == null)
            {
                throw new ArgumentNullException(nameof(targetHeaders));
            }

            foreach (var kv in targetHeaders)
            {
                headers.Add(kv.Key, kv.Value);
            }
        }