import akka.actor.ActorRef;
import java.util.Optional;
+import org.opendaylight.yangtools.concepts.Immutable;
/**
* Marker interface for data which is able to be held in a {@link Bucket}.
*
* @param <T> Concrete BucketData type
*/
-public interface BucketData<T extends BucketData<T>> {
+public interface BucketData<T extends BucketData<T>> extends Immutable {
/**
* Return the {@link ActorRef} which should be tracked as the authoritative source of this bucket's data.
* The bucket will be invalidated should the actor be reported as Terminated.