code: @Deprecated
    public static <E> ImmutableSortedSet<E> of(E e1, E e2) {
      throw new UnsupportedOperationException();
    }
docs: Not supported. <b>You are attempting to create a set that may contain a non-{@code Comparable}
  element.</b> Proper calls will resolve to the version in {@code ImmutableSortedSet}, not this
  dummy version.
  
  @throws UnsupportedOperationException always
  @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
  ImmutableSortedSet#of(Comparable, Comparable)}.</b>