Well, at the end, the decision process is like the Osiris judgement, you have to put pros and cons in a balance: performance, scalability, easy use, flexibility, etc.

From my experience working with Java,  hibernate is not the decisive criteria by itself. I think that the problem is that the architect usually does not know well enough the potential of IRIS and decide to take the easy way.

You can check it from System Monitor Log of each Mirror member. You can see an example of the log:

05/22/23-07:22:26 [SYSTEM MONITOR] System Monitor started in %SYS
05/22/23-07:26:07 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/22/23-07:33:01 [SYSTEM MONITOR] System Monitor started in %SYS
05/22/23-07:33:01 [SYSTEM MONITOR] Mirror state: Member type = Failover, Status = Synchronizing
05/22/23-07:33:31 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/22/23-07:35:55 [SYSTEM MONITOR] System Monitor started in %SYS
05/22/23-07:35:56 [SYSTEM MONITOR] Mirror state: Member type = Failover, Status = Transition
05/22/23-07:36:26 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Waiting
05/22/23-07:36:26 1 alerts posted in messages.log
05/22/23-07:40:26 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/22/23-07:58:15 [SYSTEM MONITOR] System Monitor started in %SYS
05/22/23-07:58:15 [SYSTEM MONITOR] Mirror state: Member type = Failover, Status = Waiting
05/22/23-08:06:43 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/22/23-08:10:37 [SYSTEM MONITOR] System Monitor started in %SYS
05/22/23-08:10:37 [SYSTEM MONITOR] Mirror state: Member type = Failover, Status = Waiting
05/22/23-08:34:40 1 alerts posted in messages.log
05/22/23-08:35:10 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/22/23-10:50:25 [SYSTEM MONITOR] System Monitor started in %SYS
05/22/23-10:50:25 [SYSTEM MONITOR] Mirror state: Member type = Failover, Status = Waiting
05/22/23-11:00:15 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/26/23-11:03:06 [SYSTEM MONITOR] System Monitor started in %SYS
05/26/23-11:03:07 [SYSTEM MONITOR] Mirror state: Member type = Failover, Status = Transition
05/26/23-11:03:37 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Backup
05/26/23-11:05:08 [SYSTEM MONITOR] Mirror status changed. Member type = Failover, Status = Primary
05/26/23-11:05:10 1 alerts posted in messages.log