how to ignore some member fields when using fieldGroup.bindMemberFields

Hi,
   I looked everywhere to see if I could find answer, please forgive me if this is duplicate.
   I have a formlayout whose member fields are annotated with @PropertyId. I also have form fields which are not binded by item.

Example:

PropertysetItem personItem= new PropertysetItem();
item.addItemProperty("first_name", new ObjectProperty<String>("Zaphod"));
item.addItemProperty("last_name", new ObjectProperty<String>("parrea"));

class PersonForm extends FormLayout{
    @PropertyId("firstName")
   TextField firstname = new TextField("First Name");
  @PropertyId("lastName")
    TextField lastname = new TextField("Last Name");
     //Full name not binded to any property
    TextField fullname = new TextField("Full Name");
    addComponents(fullname, firstname, lastname)
    }

     //Please not no full name in person item but included in form just for display purpose
     FieldGroup binder= new FieldGroup(personItem)
     PersonForm form = new PersonForm()
     //I get exception when I try to bind item because full name is not  item property
     //is there a way or annotation like @ignore so I can ignore fullname to be binded
     binder.bindMemberFields(form)

       //Only alternative I found is to bind each field in form  by binder.bind(form.firstName, "first_name")
but it would be nice to if I can bind in one single line like binder.bindMemberFields(form)

     //

}

Does this happen only with IndexedContainer?

Seems to me that FieldGroup uses Item.getItemProperty which is defined as "If the Item does not contain the Property, <code>null</code> is returned." but IndexedContainer implements getItemProperty so that it never returns null.