final IModel<List<? extends ObjectAdapterMemento>> choicesMementos = getChoicesModel();
if (choicesMementos != null) {
// choices drop-down
final IModel<ObjectAdapterMemento> modelObject = entityOidField.getModel();
addOrReplace(new DropDownChoicesForObjectAdapterMementos(ID_CHOICES, modelObject, choicesMementos));
// no need for link, since can see in drop-down
permanentlyHide(ID_ENTITY_LINK_WRAPPER);
// no need for the 'null' title, since if there is no object yet