@SuppressWarnings("deprecation")
@Override
public SimilarityMatrixModel get() {
logger.debug("building item-item model");
LongSortedSet itemUniverse = buildContext.getItems();
final int nitems = itemUniverse.size();
LongKeyDomain itemDomain = LongKeyDomain.fromCollection(itemUniverse, true);
assert itemDomain.size() == itemDomain.domainSize();
assert itemDomain.domainSize() == nitems;
List<List<ScoredId>> matrix = Lists.newArrayListWithCapacity(itemDomain.domainSize());