GetPropertiesListForUpdateInsert - How to select modified fields ?

Hello.

Thanks to Dennis (DevExpress Support) , he give me info about GetPropertiesListForUpdateInsert in ticket T120279
I can exclude some fields by name (code below)

C#
  
  

C#
public class UpdatedFieldsUnitOfWork : UnitOfWork {  
    public UpdatedFieldsUnitOfWork(IDataLayer dataLayer) : base(dataLayer) {}  

    protected override MemberInfoCollection GetPropertiesListForUpdateInsert(object theObject, bool isUpdate, bool addDelayedReference)  
    {  
            MemberInfoCollection result = new MemberInfoCollection(this.GetClassInfo(theObject));  
            foreach (XPMemberInfo mi in base.GetPropertiesListForUpdateInsert(theObject,  
                isUpdate,addDelayedReference))  
            {  
                // DON'T WORK:  if (mi is ServiceField || mi.GetModified(theObject))  

                //WORK BELOW  
                if (mi is ServiceField || !(mi.Name == "fLastUser"))  
                    result.Add(mi);  
            }  
            return result;  
    }  
}  

But I want to update only modified fields.

Trying to filter by

C#
mi.GetModified(theObject)  

But it always return False;

How can I filter it ?