Ok, thanks. My primary objective was just getting any javadoc generated, so ignored the 200+ warnings and just fixed the fatal errors. Thanks for going one step further.
As an aside, once I ran "mvn site" I noticed the top-level page had broken links as it seemed to assume that the javadocs from all the sub-project targets had been copied underneath the top-level target/ dir. Is there a step missing from the MOJO or something? Thanks
