code: public static <T> Comparator<T> invert(Comparator<T> comparator) {
      return (obj1, obj2) -> (-1 * comparator.compare(obj1, obj2));
    }
docs: Inverts the result of the {@link Comparator}.  Used to implement a descending sort order.
  
  @param <T> {@link Class} type of {@link Comparable} objects in the comparison.
  @param comparator the {@link Comparator} to invert.
  @return a {@link Comparator} wrapper around the given {@link Comparator} inverting the result
  of the comparison.
  @see java.util.Comparator