CAY-1557 Vertical inheritance is broken for subclasses with more than one flattened attribute

patch by Victor Antonovich - fix (some noop refactoring by aadamchik)

git-svn-id: https://svn.apache.org/repos/asf/cayenne/main/branches/STABLE-3.0@1091887 13f79535-47bb-0310-9956-ffa450edef68
3 files changed