thymeleaf iteration on a list

I'm struggling with looping on a list using thymeleaf. I've these two classes :

public class Contact {
    private String firstname;
    private String lastname;
    private String email;
    private String phone;

public class ContactForm {  
    private List<Contact> contacts;

The following controller:

@RequestMapping(value = "/get", method = RequestMethod.GET)
public ModelAndView get() {

    ContactForm contactForm = new ContactForm();
    contactForm.setContacts(Application.contacts);

    return new ModelAndView("add_contact" , "contactForm", contactForm);
}

And the view :

<form method="post" action="save.html" th:action="@{/save}"
    th:object="${contactForm}" modelattribute="contactForm">
    <table>
        <c:out value="${contactForm.contacts.size()}" />
        <tr th:each="contact : ${contactForm.contacts}">
            <td><input type="text" name="field1"
                th:field="${contact.firstname}" /></td>
            <td><input type="text" name="field2"
                th:field="${contact.lastname}" /></td>
            <td><input type="text" name="field3 "
                th:field="${contact.email}" /></td>
            <td><input type="text" name="field4"
                th:field="${contact.phone}" /></td>
        </tr>

        </tbody>
    </table>
    <br>
    <input value="Save" type="submit">
</form>

The Application.contact is a List of Contacts with 4 elements inside. The result on the browser for the line

<c:out value="${contactForm.contacts.size()}" />

is a "4" printed on the page so the object and the 4 elements are successfully passed to the view. Unfortunately it never goes into the th:each and so nothing is printed inside. What am I doing wrong here ?

Thanks for your time