Vaadin8 grid with List<~> in property

I am trying to create a grid using Vaadin and having trouble in showing data which is inside the data source. The Datasource definition is like below

public class Customer {

private String name;
private List<Contacts> contacts;

public class Contacts {

private String phonecontact;
private String emailcontact;

Now when I write the code to show data using Vaadin

  private Grid<Customer> grid=new Grid<>(Customer.class);

  private List<Customer> createCutromers(){

    List<Customer> customerList=new ArrayList<>();

    Customer cust=new Customer();
    Contacts cont=new Contacts();
    List<Contacts> contactsList=new ArrayList();
     return customerList;

Now I am trying to show Name and contacts in Grid , how should I go about it? The issue is List is shown as Object. What could be the easiest way to do it.

The output should be like

name   |   phonecontact   | emailcontacts
Rocky  |    212           | www