Field has getter/setter so make private

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/imaging/trunk@1534262 13f79535-47bb-0310-9956-ffa450edef68
Field has getter/setter so make private

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/imaging/trunk@1534263 13f79535-47bb-0310-9956-ffa450edef68