使用 spring data jpa 时，单向OnetoOne问题

private Product product =  new Product();
@OneToOne(cascade = CascadeType.ALL,fetch = FetchType.EAGER)
@JoinColumn(name = "product_id")
public Product getProduct() {
return product;
}

public void setProduct(Product product) {
this.product = product;
}

private int productId;

@javax.persistence.Column(name = "product_id")
@Basic
public int getProductId() {
return productId;
}

public void setProductId(int productId) {
this.productId = productId;
}