file upload in nested form with CPM needs dummy model

Hello,

I have an outer form, with a CPM for a business entity.

An inner form
Form<Void> uploadImageForm = new Form<>("UploadImageForm");

has a
FileUploadField uploadImageField =
new FileUploadField("UploadImageField");

and when I submit the inner form, wicket tries to find
getters/setters for UploadImageField in my business entity,
which obviously are not there:

WicketRuntimeException: No get method defined for class: class
XXXBusinessEntity expression: UploadImageField

I tried many things to work around this problem, including
Form<Void> uploadImageForm = new Form<>("UploadImageForm", null);
and
uploadImageField = new FileUploadField("UploadImageField", null);
and
setModel(null)
and some more, however the only way to really get rid of this
I found is:

FileUploadField uploadImageField = new
FileUploadField("UploadImageField", new UploadFieldModel());

static class UploadFieldModel implements IModel<List<FileUpload>> {
List<FileUpload> f;
@Override
public List<FileUpload> getObject() {
return f;

@Override
public void setObject(List<FileUpload> object) {
f=object;

@Override
public void detach() {

That doesn't sound too reasonable, does it ?
I do not need or want the value to be put to any model, is there any
more sensible way to do this ? (wicket 6.8.0 - will update soon)

Cheers, Tom.