In com.sun.syndication.feed.rss.Channel :
getLastBuildDate() always seem to return null;
getPubDate() returns pubDate correctly, but if pubDate tag isn't present in the RSS feed, content of lastBuildDate tag is returned instead.
This implies that in case both pubDate and lastBuildDate tags are filled, the contents of lastBuildDate can't be retrieved. In case only lastBuildDate is present, it can be read, but it's wrongly interpreted as pubDate.
1.0 version (of ROME Fetcher)