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
Maybe we should use less entries? 12k sounds like a lot of entries for a non-stress test...