ISPN-3594 Implementations of persistence.ParallelIterationTest fail rand...

...omly on all environmets

* also added types to the collections

Note: this should solve the random failures. If you have another solution let me know.

https://issues.jboss.org/browse/ISPN-3594
I would recommend adding a timeout to this as well, just in case.  In the timeout exception you could just set the barrier to broken.