CKEditor filters 'class' attribute from table

I'm trying to allow the class attribute on a table without allowing all tags in html.

config.allowedContent = true;

I've tried several things but none of them are working, as the editor still filters the class attribute.

I've tried:

table[class];

table[class](*);

table[class](*);table[class]{*};

*[class](*);

*(*);

*(*);*{*};

All with no result, any suggestions. Or has anyone run in to the same problem?

Kind regards,

Nick