plataformatec/simple_form — pull request #608 by andmej (2012-07-03 04:40:06+00:00)
Title: Explaining gotcha with the :collection_wrapper_class option.

I was using

<%= f.collection_check_boxes :product_ids, Product.all, :id, :name, :collection_wrapper_class => "check_boxes" %>

and it ignored the class option. I dug into the code and found out that it also requires the tag option to be there.

I think this should be documented.