Execution Listener on Usertask sometimes references global execution

Environment:

Camunda Community Edition, Apache Tomcat, Windows and Linux

Description:

An Execution Start Listener on a UserTask will not always set Variables as expected, when using ${execution.SetVariablesLocal()}. If the UserTask has a conditional boundary event, the Variable will be set on the local execution as expected. If the UserTask does not have a boundary event, the variable will be set in the parent Execution Scope.

Steps to reproduce:

Create a new BPMN Model with a single UserTask. Set up an Execution-Listener on the UserTask with event=start and expression = ${execution.SetVariablesLocal('test', null)}

Deploy and start the BPMN Process. Examine the Process Variables.

After this create a conditional boundary-event with the expression ${test != null} on the UserTask, deploy and Start the Process again.

Observed Behavior:

The variable will be in Process Instance Scope with a plain UserTask and in local Execution Scope if a conditional boundary event is present.

Expected behavior:

The variable should always be in the local scope of the UserTask Execution, consistently and not vary depending on the presence of a boundary event.

Root Cause:

Most likely the execution which is passed to Execution Start listener.

Solution Ideas:

Create an Execution on the UserTask always, even if no boundary event is present and pass this execution to the executionListener.