Thanks for the report. Bug fixed.
As per @vinothkannans’s advice, I’ve added aggregateRating as part of CreativeWork.
@vinothkannans You probably are already aware that Google’s structured data testing tool is complaining about the DiscussionForumPosting microdata for core Discourse topic views not having images. I’m not sure if that omission means the DiscussionForumPosting microdata blocks will be ignored?
