code: public final ImmutableList<E> toSortedList(Comparator<? super E> comparator) {
      return Ordering.from(comparator).immutableSortedCopy(iterable);
    }
docs: Returns an {@code ImmutableList} containing all of the elements from this {@code
  FluentIterable} in the order specified by {@code comparator}.  To produce an {@code
  ImmutableList} sorted by its natural ordering, use {@code toSortedList(Ordering.natural())}.
  
  @param comparator the function by which to sort list elements
  @throws NullPointerException if any element is null
  @since 14.0 (since 13.0 as {@code toSortedImmutableList()}).