added missing javadoc comment to justify the UnsupportedEncodingException

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/fileupload/trunk@1457973 13f79535-47bb-0310-9956-ffa450edef68
typo

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/fileupload/trunk@1457974 13f79535-47bb-0310-9956-ffa450edef68