...
@Entity
@Table(name="identity")
@SecondaryTable(name = "identity_history", pkJoinColumns = @PrimaryKeyJoinColumn(name = "dbId"))
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Identity
{
   // Identity and Version Fields
   @Id
   @GeneratedValue
   @XmlTransient
   private int dbId;
   @XmlElement(name = "identity-id")
   @Transient
   private String xmlId;
   @Version
   @XmlTransient
   private int version;

   // Data Fields
   @Embedded
   @AttributeOverrides({
       @AttributeOverride(name="attribute", column=@Column(name="username_attribute")),
       @AttributeOverride(name="versionNumber",column=@Column(name="username_versionNumber"))
   })
   private VersionedAttribute<String> username;
   
   @Embedded
   @AttributeOverrides({
       @AttributeOverride(name="attribute", column=@Column(name="password_attribute")),
       @AttributeOverride(name="versionNumber",column=@Column(name="password_versionNumber"))
   })
   private VersionedAttribute<String> password;
   
   @Embedded
   @AttributeOverrides({
       @AttributeOverride(name="attribute", column=@Column(name="isRevoked_attribute")),
       @AttributeOverride(name="versionNumber",column=@Column(name="isRevoked_versionNumber"))
   })
   private VersionedAttribute<Boolean> isRevoked;
   
   @Embedded
   @AttributeOverrides({
       @AttributeOverride(name="attribute", column=@Column(name="revocationReason_attribute")),
       @AttributeOverride(name="versionNumber",column=@Column(name="revocationReason_versionNumber"))
   })
   private VersionedAttribute<String> revocationReason;
...
}



@Embeddable
public class VersionedAttribute<T>
{
   private String versionNumber;
   private T attribute;
   
   public VersionedAttribute()
   {
      
   }

   public VersionedAttribute(String versionNumber, T attribute)
   {
      super();
      this.versionNumber = versionNumber;
      this.attribute = attribute;
   }
...
}