[eclipselink-dev] Preliminary patch for bug 235433: Can't customize Conn

["Andrei Ilitchev" <andrei.ilitchev@xxxxxxxxxx>]

Added a preliminary patch to 
https://bugs.eclipse.org/bugs/show_bug.cgi?id=235433 : Can't customize 
ConnectionPolicy through JPA.

The patch is fully functional and includes tests.
It allows customization of ConnectionPolicy through the properties passed to
createEntityManager (see the new properties in EntityManagerProperties).
It also allows creation of ExclusiveIsolatedClientSession in case no 
isolated
descriptors specified.
The patch is called "preliminary" because
1. It uses ExclusiveConnectionMode with Transaction, IsolatedSession and
Session values which hasn't been approved yet (and well may be rejected);
2. It lacks many comments.

Please send your thoughts,

Thanks,

Andrei