minor: JavaDoc improvements only

git-svn-id: https://svn.apache.org/repos/asf/stanbol/branches/release-0.12@1559654 13f79535-47bb-0310-9956-ffa450edef68
minor: added log.isTraceEnabled() block over two trace level log statements

git-svn-id: https://svn.apache.org/repos/asf/stanbol/branches/release-0.12@1559656 13f79535-47bb-0310-9956-ffa450edef68