hibernate中的ManyToMany关系在初始化应用程序时不会将值插入到连接表中

@Entity
public class User {
    @Id
    private Long id;
    
    // other attributes and getters/setters
    
    @ManyToMany
    private Set<Role> roles;
    
    // getters/setters
}

@Entity
public class Role {
    @Id
    private Long id;
    
    // other attributes and getters/setters
    
    @ManyToMany(mappedBy = "roles")
    private Set<User> users;
    
    // getters/setters
}

User user1 = new User();
user1.setId(1L);

User user2 = new User();
user2.setId(2L);

Role role1 = new Role();
role1.setId(1L);

Role role2 = new Role();
role2.setId(2L);

user1.getRoles().add(role1);
user1.getRoles().add(role2);

user2.getRoles().add(role1);

session.save(user1);
session.save(user2);

@ManyToMany(cascade = CascadeType.ALL)
private Set<Role> roles;