[xwiki-users] List of groups that a user belongs to

Is it possible to get a list of all users that a user belongs to using velocity or groovy? The getAllMatchedUsers() method in the XWikiGroupService looks like it would do what I need but this does not seem to be exposed in the xwiki api for use in velocity/groovy? http://maven.xwiki.org/site/xwiki-core-parent/xwiki-core/apidocs/com/xpn/xwi... Radek Rekas