SLING-2993 : Properly tag and annotate interfaces and classes

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1519572 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare release sling-18

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1519573 13f79535-47bb-0310-9956-ffa450edef68