public static <T> Stream<List<T>> of(final Collection<T> items) {
        return CombinationUtil.of(items);
    }
Creates and returns all possible combinations of the given elements.

The order of the combinations in the stream is unspecified.

@param <T> element type
@param items to combine
@return all possible combinations of the given elements
common-parent/combinatorics/src/main/java/com/speedment/common/combinatorics/Combination.java