public Collection<String> getAllItemIDs() {
    Collection<String> allItemIDs = UnifiedSet.newSet(Y.size());
    Y.addAllIDsTo(allItemIDs);
    return allItemIDs;
  }
public Collection < String > getAllItemIDs ( ) { Collection < String > allItemIDs = UnifiedSet . newSet ( Y . size ( ) ) ; Y . addAllIDsTo ( allItemIDs ) ; return allItemIDs ; }
@return all item IDs in the model