gistfile1.java

@MappedSuperclass
public abstract class BaseEntity {

    private Long id;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

}

@Entity
@Table(name="slot_id")
public class SlotId extends BaseEntity {

    private String slotId;

    public void setSlotId(String slotId) {
        this.slotId = slotId;
    }

    public String getSlotId() {
        return slotId;
    }
}