prevent ClassCastException as now return a Collection rather than a List

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1580693 13f79535-47bb-0310-9956-ffa450edef68
use directly query filtering

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1580694 13f79535-47bb-0310-9956-ffa450edef68