public static string PathAndChecksum(string filePath)
        {
            return $"{filePath}?v={AppendFileChecksum(filePath)}";
        }

        static string AppendFileChecksum(string filePath)
        {
            return _appCtx.ApplicationCache.RuntimeCache.GetCacheItem(filePath, () =>
            {
                var fullFilePath = _httpCtx.Server.MapPath(filePath);

                var fileStream = File.OpenRead(fullFilePath);

                return CryptoHelpers.GetSHASum(fileStream);

            }).ToString();
        }

        /// <summary>
        /// SHA 256 sum of input stream
        /// </summary>
        public static string GetSHASum(Stream input)
        {
            var hasher = new SHA256Managed();
            byte[] result = hasher.ComputeHash(input);

            string checkhash = BitConverter.ToString(result).Replace("-", "");

            return checkhash;
        }