@Override
  public Set<VItem> get(@NotNull K key) throws IOException {
    Items<VItem> items = items(key);
    if (items == null) {
      return null;
    }
    @SuppressWarnings("SSBasedInspection")
    ObjectOpenHashSet<VItem> result = new ObjectOpenHashSet<>();
    items.forEach(item -> {
      result.add(item);
    });
    return result;
  }
@Override
  public Set<VItem> get(@NotNull K key)