After Enabling Elytron Support in My Resource Adapter, I Can't Set an Initial Pool Size for My Connection Pool

Issue

I am trying to configure my JMS resource adapter (IBM MQ, in this case) with Elytron security support. When I set "elytron-enabled" in my resource adapter security settings I can't enable prefill or set an initial-pool-size without seeing errors in the logs on startup. How can I prefill my connection pool with elytron-enabled set to "true?"