code: @NotNull
      public static <T> Comparator<T> reversed(@Nullable Comparator<T> comparator) {
          return Collections.reverseOrder(comparator);
      }
docs: Returns a comparator that reverses the order of the specified comparator.
  If the specified comparator is {@code null}, this method is equivalent
  to {@link #reverseOrder()}.
  
  @param <T> the type of the objects compared by the comparator
  @param comparator  a comparator to be reversed
  @return a comparator
  @see Collections#reverseOrder(java.util.Comparator)
  @throws NullPointerException if {@code comparator} is null