JPA @ElementCollection @Enumerated not inserting

I am trying to implement basic user/roles

A user can have zero to many roles.

public enum Role {
   ROLE_USER,
   ROLE_ADMIN;
 }
 
 @Entity
 @Table(name = "USERS")
 public class User implements Serializable {
 
   private static final long serialVersionUID = 2936736450886451500L;
   private Long id;
   private Set<Role> roles = new HashSet<Role>();
 
   @Id
   @Column(name = "ID")
   @GeneratedValue
   public Long getId() {
     return id;
   }
 
   @SuppressWarnings("unused")
   private void setId(Long id) {
     this.id = id;
   }
 
   @ElementCollection(targetClass=Role.class)
   @JoinTable(name = "USER_ROLES", joinColumns = @JoinColumn(name = "USER_ID"))
   @Enumerated(EnumType.STRING)
   @Column(name = "role", nullable = false)
   public Set<Role> getRoles() {
     return roles;
   }
 
   public void setRoles(Set<Role> roles) {
     this.roles = roles;
   }
 
   public void addRole(Role role) {
     roles.add(role);
   }
 
 }
 

My Unit Test

@RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration({"classpath:/META-INF/spring/resources/resource-context.xml", "classpath:/META-INF/spring/services/persistence-context.xml"})
 public class UserDaoJpaImplTest {
 
 @Autowired
 UserDao userDao;
 
 @Transactional
 @Test
 public void testCreate() {
     User user = new User();
     user.addRole(Role.ROLE_USER);
     user.addRole(Role.ROLE_ADMIN);
     userDao.create(user);
 
     Assert.assertNotSame(user.getId(), 0);
 }
 

the problem is, that jpa (backed by hibernate), is not doing the insert on the USER_ROLES table (it is creating it correctly, with the correct composite PK (ROLE, USER_ID), and FK to user.

I can see in the console, that only a single insert is being done, on the user

Hibernate: insert into USERS values ( )
 

I assume I am just missing something simple.

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