Many-to-many não persiste na tabela de Join

@Entity
@Table(name = "users")
public class User implements Serializable {

	@Id @GeneratedValue(strategy = GenerationType.AUTO)
	private Long id;
	
	@Column
	private String email;
	
	@Column(name = "hashed_password")
	private String password;

	@Column(name = "account_status")
	private boolean accountStatus;

	@ManyToMany(targetEntity = Role.class, fetch = FetchType.LAZY, cascade = CascadeType.ALL)
	@JoinTable(name = "users_has_roles",
            joinColumns = @JoinColumn(name = "users_id"),  
            inverseJoinColumns = @JoinColumn(name = "roles_id")  
    )  
	private Collection<Role> roles;

	public boolean addRole(Role role) {
		if(roles == null) {
			roles = new HashSet<Role>();
		}
		return roles.add(role);
	}
     //getters and setters
}

@Entity
@Table(name = "roles")
public class Role implements Serializable {

	private static final long serialVersionUID = -8141540060286714020L;

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer id;
	
	@Column
	private String name;
}