Prefill is a combination of things - you have the PrefillPool check and the min-pool-size check. However you are missing the ironjacamar/AbstractPrefillPool.java at 1.0 · ironjacamar/ironjacamar · GitHub checks atm.
Hmm, I do not see this checked in
seems that 1.2 calls isPrefill() which does getPoolConfiguration().getMinSize() > 0 and ignores strictMin as well.
Does that mean that it is broken in 1.2 as well?
Prefill in 1.2 is guarded by the method call plus the local variable - in 1.0 to have to combined those checks. Flushing is different in 1.2, and there are additional checks in the ManagedConnectionPool implementation around this.