docs: public static <T, C extends Comparable<? super C>> List<T> sortInplaceBy(List<T> list,
  			final Functions.Function1<? super T, C> key) {
  		if (key == null)
  			throw new NullPointerException("key");
  		Collections.sort(list, new KeyComparator<T, C>(key));
  		return list;
  	}