If a CMR resource is deployed concurrently then it will overwrite the list of resources that are expected to behave as CMR -------------------------------------------------------------------------------------------------------------------------- Key: WFLY-13632 URL: https://issues.redhat.com/browse/WFLY-13632 Project: WildFly Issue Type: Bug Components: Transactions Reporter: Thomas Jenkinson Assignee: Michael Musgrove Priority: Blocker Inspecting https://github.com/wildfly/wildfly/blob/master/transactions/src/main/java... we can see that it will overwrite the map in https://github.com/jbosstm/narayana/blob/48818111d12d2e51b52082a00bcb6060... because it first get's a copy of a map (https://github.com/wildfly/wildfly/blob/master/transactions/src/main/java... -> https://github.com/jbosstm/narayana/blob/48818111d12d2e51b52082a00bcb6060...) so the maps won't be equal. This will result in WildFly overwriting the list of resources that Narayana will treat as CMR.