TransactionTable.enlist calls transactionSynchronizationRegistry.registerInterposedSynchronization(sync); but when an async operation is invoked with implicit transaction, the thread-local transaction is suspended. That can result in

java.lang.NullPointerException
	at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936)
	at org.jboss.as.txn.service.internal.tsr.TransactionSynchronizationRegistryWrapper.registerInterposedSynchronization(TransactionSynchronizationRegistryWrapper.java:69)

I guess that since TransactionSynchronizationRegistry does not offer a variant that would accept the transaction as parameter we need to wrap the call with resume & suspend.