code: @Deprecated
    public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
      return checkNotNull(iterable);
    }
docs: Construct a fluent iterable from another fluent iterable. This is obviously never necessary,
  but is intended to help call out cases where one migration from {@code Iterable} to {@code
  FluentIterable} has obviated the need to explicitly convert to a {@code FluentIterable}.
  
  @deprecated instances of {@code FluentIterable} don't need to be converted to {@code
  FluentIterable}