The upgrade to JGroups 4.0 will break the JGroups DistributedWorkManager implementation in IronJacamar (which uses JGroups 3.x). JGroups is only used to broadcast/receive commands to the cluster. This can be easily implemented using the WildFly clustering API. Such an implementation will simplify the transition to JGroups 4.0 and future-proof WildFly from any new API breakage.

Additionally, the JGroupsTransport in ironjacamar has some issues:

• Performs blocking operations on view change
• Does a lot of unnecessary serialization of Address
• Doesn't leverage multicasts