Transactions resulting in OptimisticLockingExcepetion are never committed nor rolled back

[amadfida]

When OptimisticLockingException are thrown during session.flush() as part of doCommit(), it has been observed that those transactions are not rolled back and are left open and Neo4j server keep those transaction alive, and keeping any locks on objects as well. There so no default transaction timeout in Neo4j, hence resulting in complete lock till restart.

https://github.com/spring-projects/spring-framework/blob/master/spring-tx/src/main/java/org/springframework/transaction/support/AbstractPlatformTransactionManager.java#L128 seems that we should set that to true in Neo4jDatastoreTransactionManager to handle roll backs during commit failures.

[amadfida]

@graemerocher @jameskleeh please let me know if you need more info.