Transaction issues with Timer catch event

If I repeatedly start new process containing intermediate Timer event in Kie server, I get exception listed in attachments. This exception happens irregularly, though I was able to reproduce it in reproducer runs.

Attachments contains complete Maven/server logs of running reproducer - 2 runs. They seem to have one error stacktrace in common, see: "IJ000311: Throwable from unregister connection: java.lang.IllegalStateException: Trying to return an unknown connection2!".

It may possibly be affected by[1].

Reproducer: [2]

[1] https://github.com/droolsjbpm/jbpm/pull/611
[2] https://github.com/droolsjbpm/droolsjbpm-integration/pull/717