Unit test for validate-atmost-once-period.


Enable validation.

Iteration 1:
Appclient first calls an ejb method to initialize the connection pool.

After first call to ejb, database is restarted.

Iteration 2:
Appclient calls the same ejb method. With validation on, all bad connections are
removed and newly created. Test must work fine.

Enable validateAtmostOncePeriod (set 30 seconds)

database is restarted.

Iteration 3:
Appclient calls the same ejb method. Since validateAtmostOncePeriod is set, connection
will not be validated and this method must throw exception.
[This is a negative test to verify validateAtmostOncePeriod feature. 
Purpose of validateAtmostPeriod is to optimize/miminize the validation calls to database.]