Don't rely on direct access to internal fields

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1477622 13f79535-47bb-0310-9956-ffa450edef68
Field can be private

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1477624 13f79535-47bb-0310-9956-ffa450edef68