表A

@ManyToOne
private B b;
表B

@Column(length = 10, nullable = false, unique = true)
private String name;

@OneToMany(cascade = CascadeType.REFRESH, mappedBy = "b")
private Set alist;
Service(已加入@Service和@Transactional)

A a = new A();

a.setB(new B(1));

service.save(a);

这时报错：

not-null property references a null or transient value : com.entity.B.name

可是我在JUnit里面用同样的确可以 ，这是怎么回事啊