/// <summary>
    /// Create the user on the server
    /// </summary>
    /// <param name="userId"></param>
    /// <param name="groupId"></param>
    /// <param name="userAuthentication"></param>
    /// <returns>TRUE: Suceess</returns>
    private bool AddUserToGroup(string userId, string groupId)
    {
        //ref: https://help.tableau.com/current/api/rest_api/en-us/REST/rest_api_ref.htm#add_user_to_group
        var sb        = new StringBuilder();
        var xmlWriter = XmlWriter.Create(sb, XmlHelper.XmlSettingsForWebRequests);

        xmlWriter.WriteStartElement("tsRequest");
        xmlWriter.WriteStartElement("user");
        xmlWriter.WriteAttributeString("id", userId);
        xmlWriter.WriteEndElement(); //</user>
        xmlWriter.WriteEndElement(); //</tsRequest>
        xmlWriter.Close();

        var xmlText = sb.ToString(); //Get the XML text out

        //Generate the MIME message

        //Create a web request
        var urlAddUserToGroup = _onlineUrls.Url_AddUserToGroup(_onlineSession, groupId);
        var webRequest        = this.CreateLoggedInWebRequest(urlAddUserToGroup, "POST");

        TableauServerRequestBase.SendPostContents(webRequest, xmlText);

        //Get the response
        var response = GetWebReponseLogErrors(webRequest, "add user to group");

        using (response)
        {
            var xmlDoc = GetWebResponseAsXml(response);

            //Get all the workbook nodes
            var nsManager = XmlHelper.CreateTableauXmlNamespaceManager("iwsOnline");
            var xNodeUser = xmlDoc.SelectSingleNode("//iwsOnline:user", nsManager);

            if (xNodeUser == null)
            {
                StatusLog.AddError("Add user to group failed. Repsonse was not a USER node");
                return(false); //Failure
            }

            return(true); //Success
        }
    }