OAK-1160: Generic interfaces for operation tasks
Adding @NonNull annotations and TYPE constant

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1578805 13f79535-47bb-0310-9956-ffa450edef68
OAK-1160: Generic interfaces for operation tasks
Per component interfaces for management tasks

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1578806 13f79535-47bb-0310-9956-ffa450edef68