don't call overrideable method from constructor

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1456140 13f79535-47bb-0310-9956-ffa450edef68
avoid static final

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1456142 13f79535-47bb-0310-9956-ffa450edef68