@Entity
@AssociationOverrides({
   @AssociationOverride(name = "car.id", joinColumns = @JoinColumn(name = "id")),
   @AssociationOverride(name = "car.revision", joinColumns = @JoinColumn(name = "revision"))
                })
public class Car implements Serializable
{
   private static final long      serialVersionUID   = -3225046848847754211L;

   @EmbeddedId
   private CarPk   carPk;

   //..

   @Override
   public int hashCode()
   {
      //..
   }

   @Override
   public boolean equals(final Object obj)
   {
      //..
   }
}



@Embeddable
public class CarPk implements Serializable
{
   @GeneratedValue(strategy = GenerationType.AUTO)
   private Long   id;
   private Long   revision;

   public CarPk()
   {

   }

   public CarPk(final Long id, final Long revision)
   {
      this.id = id;
      this.revision = revision;
   }

   // ..

   @Override
   public int hashCode()
   {
      // ..
   }

   @Override
   public boolean equals(final Object obj)
   {
      // ..
   }
}