code: public static <T> Stream<T> ofNullable(Iterable<T> iterable) {
          return null == iterable ? Stream.empty() : stream(iterable);
      }
docs: Converts a nullable Iterable into a Stream.
  @param iterable The iterable to stream.
  @param <T> The type of the iterable
  @return Stream of the values returned by the iterable, or an empty stream if the iterable is null