public string RefreshAuthorizationData(AuthParameters authParameters)
        {
            if (!String.IsNullOrEmpty(authParameters.Error))
            {
                throw new Exception(authParameters.Error);
            }

            // make sure we have the necessary parameters
            ValidateParameter("storeUrl", authParameters.ServerUrl);
            ValidateParameter("clientId", authParameters.ClientId);
            ValidateParameter("GrantType", authParameters.GrantType);
            ValidateParameter("RefreshToken", authParameters.RefreshToken);

            // get the access token
            string accessToken = _apiAuthorizer.RefreshToken(authParameters.RefreshToken, authParameters.GrantType);

            return(accessToken);
        }