[eclipselink-dev] checked in 243993 to 2.3

[Christopher Delahunt <christopher.delahunt@xxxxxxxxxx>]

https://bugs.eclipse.org/bugs/show_bug.cgi?id=243993

243993 - RepeatableWriteUnitOfWork's usage of UnitOfWorkImpl can cause 
ConcurrentModificationException
-trivial change to RepeatableWriteUnitOfWork to clone cloneMap passed to 
the calculateChange method
- test added to LifecycleCallbackJunitTest that executes a query in an 
EclipseLink native preUpdate event (vs a JPA event).

checked into 2.3
reviewed by Michael O'Brien