private string CalculateETag() { var fileInfo = new FileInfo(_physicalPath); var lastWriteTime = fileInfo.LastWriteTimeUtc.Ticks; var creationTime = fileInfo.CreationTimeUtc.Ticks; var size = fileInfo.Length; var cacheKey = $"{_presetName}_{_physicalPath}_{size}_{lastWriteTime}_{creationTime}_{_version}"; return(CryptographyHelper.CalculateSHA1(cacheKey)); }