public class Billing implements Identity {
    @NotBlank
    @FieldProp(name = "First Name")
    private String firstName;
    @FieldProp(name = "Last Name")
    private String lastName;
    @FieldProp(name = "Company")
    private String company;
    @FieldProp(name = "Address")
    private Address address;
    @Valid
    @FieldProp(name = "Phone")
    private List<PhoneNumber> phoneNumbers;
    @FieldProp(name = "Email")
    private String email;