[xwiki-users] Lucene search "object:" not working ?

Hi, Following this page<http://code.xwiki.org/xwiki/bin/view/Applications/SearchApplicationLuceneSearchQueryHelp>, I was interested in using lucene to search for pages containing specific objects using, for example, syntax like "object:XWiki.XWikiUsers AND jbousque". I did not manage to have any results, with different classes. I also tested using only "object:XWiki.XWikiUsers", expecting to retrieve the list of users, but again no result at all. Am I missing something ? Thanks, Jeremie