Start Timer Event returns timer instance to the process

When you execute attached process com.myspace.timerproject.TimerStartEventTest.v1.0.bpmn2 you will see that Timer Start Event inside of a Event sub-process sending TimerInstance instance to the process (see trace below). It is not consistent with Top level Timer Start Event and danger by it's nature.

14:12:42,718 INFO  [stdout] (EJB default - 6) class org.jbpm.process.instance.timer.TimerInstance
14:12:42,718 INFO  [stdout] (EJB default - 6) TimerInstance [id=1, timerId=1, delay=3000, period=0, jobHandle=EjbGlobalJobHandle [uuid=1-1-1], activated=Fri Mar 23 14:12:39 CET 2018, lastTriggered=Fri Mar 23 14:12:42 CET 2018, processInstanceId=1]

Behaviour should be consistent and Timer Start Event shuouldn't return any value in all situations.

For more info see discussion in RHPAM-571.