public FileWriter(MultipleFilesHandler handler, ManifestFile manifestFile, FileTarget target, ulong expectedBytes)
 {
     _handler      = handler;
     Target        = target;
     ManifestFile  = manifestFile;
     ExpectedBytes = expectedBytes;
 }
            public async ValueTask DisposeAsync()
            {
                await CancelAsync();

                _handler = null;
            }