OPENJPA-2285: Recommitted DataCacheStoreManager improvement.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@1570016 13f79535-47bb-0310-9956-ffa450edef68
(cherry picked from commit f01f7c47216056a1fbe13272b6aea282618da7ac)