Fail to persist sub class

[xtia004]

I have the following code. CreditCardPayment is inherited from Payment and added some extra fields.

@Entity
@Table(name = "PAYMENT")
@Name("payment")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="PAY_METHOD", discriminatorType=DiscriminatorType.STRING, length=2)
public class Payment implements java.io.Serializable {

 private static final long serialVersionUID = 581797746676908701L;

 @TableGenerator(name = "objectIdGen", table = "OP_SEQUENCE_GENERATOR", pkColumnName = "GEN_KEY", valueColumnName = "GEN_VALUE", pkColumnValue = "OBJECT_ID", initialValue = 1, allocationSize = 1)
 @Id
 @GeneratedValue(strategy = GenerationType.TABLE, generator = "objectIdGen")
 @Column(name = "OBJECT_ID", nullable = false)
 private Long objID;

 @Column(name = "PAYMENT_CODE", length = 10, nullable = false)
 private String paymentCode;

 @Column(name = "PAID_AMOUNT", nullable = false)
 private BigDecimal paidAmount;

 @Column(name = "PAID_DATE", nullable = false)
 @Basic @Temporal(TemporalType.DATE)
 private Date paidDate;

 @Column(name = "PAY_METHOD", length = 2, nullable = false)
 private String payMethod;

 ...
}



@Entity
@Table(name = "CREDITCARD_PAYMENT")
@Name("creditCardPayment")
@DiscriminatorValue("CC")
public class CreditCardPayment extends Payment {

 private static final long serialVersionUID = -4171432845137278960L;

 @JoinColumn(name = "CREDITCARD_ID")
 @ManyToOne
 private CreditCard creditCard;

 @Column(name = "AUTH_CODE", length = 15, nullable = false)
 private String authCode;

 @Column(name = "DPS_TXN_REF", length = 31, nullable = false)
 private String dpsTxnRef;

 ...
}

When I create object of CreditCardPayment using following code and persist it. I got exception:

Caused by: org.hibernate.PropertyValueException: not-null property references a null or transient value: com.oneplace.payment.CreditCardPayment._paymentsBackref

I have checked I didn't miss any fields. What's the property "paymentsBackref" from and how to set it. Please somebody help me.

CreditCardPayment payment = new CreditCardPayment();
payment.setAuthCode(authCode);
payment.setDpsTxnRef(dpsTxnRef);
payment.setCreditCard(card);
payment.setPaymentCode(paymentCode);
payment.setPaidAmount(getSelectedSum());
payment.setPaidDate(DateTimeUtil.getCurrentDate());
payment.setPayMethod(payMethod);
...
em.persist(payment);

[xtia004]

I found the problem was caused by there is one-to-many relationship defined at another entity to Payment, which caused a foreign key created at Payment.

One point is the exception message is not precise and doesn't make much sense.