https://github.com/scottmarlow/wildfly/tree/WFLY-20393_addonetransformer_per_persistenceunit has commit https://github.com/scottmarlow/wildfly/commit/1b111b64cd94b57299c14ffc7a251a65937c987c that I think can cause an OOM when run with the WildFly max heap size set to the default (max of 512mb) that can be worked around by increasing max memory to around 2000 mb. 

To recreate, build branch https://github.com/scottmarlow/wildfly/tree/WFLY-20393_addonetransformer_per_persistenceunit and start the WildFly server with TRACE logging enabled for org.jboss.as.jpa.  Then change into testsuite/integration/basic and run "mvn clean install -Dtest=org.jboss.as.test.integration.jpa.hhh18901.JpaJarFileTestCase".

The test will fail with OOM errors received from the WildFly server.

Action to discover why this happens:

1. JAVA_OPTS="-XX:+HeapDumpOnOutOfMemoryError"
   
   # Start WildFly with a larger than 512mb max memory size but not too large that the error is avoided and just small enough (max memory) that the heapdump can be collected on the first oom reached.
   # Run the test
   # From the captured heapdump, figure out what the cause of the OOM is and update this issue with that information.