No need to convert to StringBuffer first

git-svn-id: https://svn.apache.org/repos/asf/creadur/rat/trunk@1483923 13f79535-47bb-0310-9956-ffa450edef68
StringBuffer => StringBuilder

git-svn-id: https://svn.apache.org/repos/asf/creadur/rat/trunk@1483924 13f79535-47bb-0310-9956-ffa450edef68