code: public static <ItemType> BootstrapIterator<ItemType> forData(Iterable<? extends ItemType> data,
        Random rng) {
      return new BootstrapIterator<ItemType>(data, rng);
    }
docs: Creates a {@code BootstrapIterator} which samples from the provided {@code data}.  This method
  takes in a {@code Random} to ensure determinism.