* @param <T> Identifier class, must conform to API contract outlined by {@link Identifier}, even if it does not
* implement it.
*/
-// FIXME: 4.0.0: consider requiring "T extends Serializable"
+// FIXME: 5.0.0: consider requiring "T extends Serializable"
public interface Identifiable<T> {
/**
* Return this objects Identifier.