TransactionOutboxImpl#scheduler can't be shutdown without stopping the whole JVM

[reda-alaoui]

Hello,

Our application is deployed as a WAR in a standalone Tomcat. The application can 'reboot' without rebooting the whole JVM.
It seems there is no way to programmatically stop TransactionOutboxImpl#scheduler or to provide it.

Could you please make TransactionOutbox closeable with a close method shutting down the executor?