How to pass marked records from grid to sysoperations framework in AX

Controller class

/// <summary>
/// 
/// </summary>
class Sales_UpdateMoDSalesOrderController extends SysOperationServiceController
{
    public static Sales_UpdateMoDSalesOrderController construct(Args _args)
    {
        Sales_UpdateMoDSalesOrderController  controller = new Sales_UpdateMoDSalesOrderController(classStr( Sales_UpdateMoDSalesOrderService ),
                                                                                                        methodStr( Sales_UpdateMoDSalesOrderService, updateMoDSalesOrder ),
            SysOperationExecutionMode::Synchronous);

        controller.parmArgs( _args );

        return controller;
    }

    public static void main(Args _args)
    {
        Set                                     recordSet;
        SalesTable                              salesTable;
        MultiSelectionHelper                    multiselectionHelper;
        Sales_UpdateMoDSalesOrderContract    dataContract;
        Sales_UpdateMoDSalesOrderController  controller;

        controller = Sales_UpdateMoDSalesOrderController::construct( _args );

        // Get marked records from calling form
        if (_args && _args.caller() is FormRun)
        {
            recordSet = new Set(Types::Record);
            multiselectionHelper = MultiSelectionHelper::createFromCaller(_args.caller());
        
            salesTable = multiselectionHelper.getFirst();

            while (salesTable)
            {
                recordSet.add(salesTable);
            
                salesTable = multiselectionHelper.getNext();
            }
        }

        // Put records from calling datasource into dataContract
        dataContract = controller.getDataContractObject();

        if (dataContract is Sales_UpdateMoDSalesOrderContract)
        {
            dataContract.parmRecordCon(recordSet.pack());
        }

        controller.startOperation();
    }
}

Contract class

/// <summary>
/// The data contract for Intercompany update of Mode of delivery
/// </summary>
[
    DataContract,
    SysOperationGroup('GeneralGroup',"@SYS81043",'1',FormArrangeMethod::Vertical)
]
class Sales_UpdateMoDSalesOrderContract implements SysOperationInitializable, SysOperationValidatable
{
    UpsModeOfDelivery upsModeOfDelivery;
    container            recordCon;

    /// <summary>
    /// Indicates whether the contract is valid.
    /// </summary>
    /// <returns>
    /// A Boolean value that indicates whether the contract is valid.
    /// </returns>
    public boolean validate()
    {
        boolean isValid = true;
        return isValid;
    }

    /// <summary>
    /// Initailizes the default values to parameters.
    /// </summary>
    public void initialize()
    {
    }

    /// <summary>
    /// Method used to specify the data memmber attribute
    /// </summary>
    /// <param>
    /// <name>parmShipmentDate</name>is used to set and get the shipmentDate
    /// </param>
    [
         DataMember,
         SysOperationGroupMember('GeneralGroup'),
         SysOperationDisplayOrder('1'),
         SysOperationLabelAttribute(literalstr("@Warehouse:UpsModeOfDelivery"))
    ]
    public UpsModeOfDelivery parmUpsModeOfDelivery( UpsModeOfDelivery _upsModeOfDelivery = upsModeOfDelivery )
    {
        upsModeOfDelivery  =  _upsModeOfDelivery;

        return upsModeOfDelivery;
    }

    /// <summary>
    /// Method used to specify the data memmber attribute
    /// </summary>
    /// <param name = "_recordCon"></param>
    /// <returns></returns>
    [DataMemberAttribute, SysOperationControlVisibilityAttribute(false)]
    public container parmRecordCon(container _recordCon = recordCon)
    {
        recordCon = _recordCon;

        return recordCon;
    }

}

Service class

class Sales_UpdateMoDSalesOrderService
{
    /// <summary>
    /// Creates transfer order for from and to wareshouse combination
    /// </summary>
    /// <param name = "_contract">TransferOrderCreateContract from dialog</param>
    public void updateMoDSalesOrder(Sales_UpdateMoDSalesOrderContract _contract)
    {
        Set                     recordSet;
        Common                  record;
        SalesTable              salesTable;
        SetEnumerator           se;
        ModeOfDeliverySetup  smModeOfDeliverySetup;

        // Process records
        if (conLen(_contract.parmRecordCon()) > 0)
        {
            recordSet = Set::create(_contract.parmRecordCon());
            se = recordSet.getEnumerator();
            while (se.moveNext())
            {
                record = se.current();

                switch (record.TableId)
                {
                    case tableNum(SalesTable):
                        salesTable = record;
                        salesTable.DlvMode = _contract.parmUpsModeOfDelivery();

                        info(strFmt("%1 %2", salesTable.SalesId, salesTable.DlvMode));
                        break;

                    default:
                        break;
                }
            }
        }
    }

}