Looking in the source, turns out they don't support lists, so you can't do subdatasets without a flat file (which is how the subdataset is done in the Jasper Reports example). However, one of my devs has dropped a patch here: http://community.jaspersoft.com/jasperreports-library/issues/2500-0 If you have a JSON List, declare it as an InputStream and send it to your subdataset. All we need now is someone to review the patch.
