public string getCheckSum(string fileName)
        {
            SessionOptions sessionOptions = new SessionOptions
            {
                Protocol = Protocol.Ftp,
                HostName = this.endpointBaseUriString,
                UserName = this.userName,
                Password = this.password,
                FtpMode = FtpMode.Passive
            };

            string result = null;

            try
            {
                using (Session session = new Session())
                {
                    session.Open(sessionOptions);
                    var command = $"XMD5 '{fileName}' SP EP ;";

                    var transferResult = session.ExecuteCommand(command);
                    transferResult.Check();

                    result = transferResult.Output;

                    //var transferResult = session.CalculateFileChecksum("md5", fileName);
                }
            }
            catch (Exception ex) {
                throw ex;
            }

            return result;
        }