Binder with call backend

I have created two comboboxes, I would like to use the binder and to make a call to the controller which gives me the list of objects of my bean. The problem is that when I go to binder.setBean and I go to set the combo I get a weird error. Can someone help me?
The steps are as follows:
ComboBox<String> combo1 = new ComboBox<>(); ComboBox<String> combo2 = new ComboBox<>(); Binder <Person> binder = new Binder<>(Person.class) Lis<Person> persons = controller.findAll(); persons.foreach(elem -> binder.setBean(elem)); binder.forField(combo1).bind(Person::getName);

Why are you iterating over all person instances? Normally the binder is used to edit one person.