@Nullable
  public <Item> SearchEverywhereContributor<Item> getContributorForIndex(int index) {
    //noinspection unchecked
    return (SearchEverywhereContributor<Item>)listElements.get(index).getContributor();
  }
@Nullable
  public <Item> SearchEverywhereContributor<Item> getContributorForIndex(int index)