Help with JPA Inheritance Relationship Mapping

Question

Perhaps someone can help with this. I'm trying to figure out how to map what seems like a simple data model using JPA. But it is not working.
@Entity
public class Account {
    @OneToOne(cascade=CascadeType.ALL)
    private AbstractPaymentMethod paymentMethod;
@Entity
@MappedSuperClass
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="__CLASS__", discriminatorType=DiscriminatorType.STRING, length=20)
@DiscriminatorValue("AbstractPaymentMethod")
public abstract class AbstractPaymentMethod {
@Entity
@Table(name="payment_method")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="__CLASS__", discriminatorType=DiscriminatorType.STRING, length=20)
@DiscriminatorValue("CreditCardPaymentMethod")
@SuppressWarnings("serial")
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
public class CreditCardPaymentMethod extends AbstractPaymentMethod {
    @Column
    private String expirationDate;
}The problem is, when I add a CreditCardPaymentMethod to an account like this...
Account account = new Account();
CreditCardPaymentMethod m = new CreditCardPaymentMethod();
account.setPaymentMethod(m);
em.persiste(account);... The entity manager attempts to save account.creditCardPaymentMethod as an AbstractPaymentMethod.
Surely I'm doing something horribly wrong. Is there something I'm missing here?
Thanks for any help.

Answer 1

Thank you! You saved my life. After removing @MappedSuperClass, all is well.
The entity manager is now saving my CreditCardPaymentMethod objects as CreditCardPaymentMethod classes instead of AbstractPaymentMethod classes.