public string FormatFileName(string filename)
                {
                    string conflictToken = filename == _supportingFile.FileName
                        ? _supportingFile.FileNameUniqueToken
                        : Guid.NewGuid().ToString();

                    if (conflictToken == "0") //don't include the conflict token for the first version of the file.
                    {
                        conflictToken = null;
                    }
                    return(_fileUploader.FormatUploadFileName(filename, conflictToken));
                }