Stunner - Compensation events

Add support for the following compensation events to the palette:

1. Start event
2. Boundary interrupting event
3. Throwing event
4. End event

As Aimee I want to add compensation events so that I can rollback the actions that were done during the execution.

The intermediate throwing event doesn't need to have the ASYNC option available.

As Aimee I want to reference the compensation activities which should rollback so that 2+ different compensation events happening in the same process model.

Implementation details & specification of the supported properties per event type:

StartEvent:
The start compensation event only apply for the "Event Sub-Processes"

• Event Sub-Process
  • Name:
  • Documentation:
  • IsInterrupting: Not shown in the UI. Internally expected value by jbpm engine is false.
  • UI: Event border is shown solid in the BPMN2 standard. (even when the is interrupting value is internally set to false)

Boundary event:

• Name:
• Documentation:
• CancelActivity: not apply for this event.
• UI: Event is shown solid in the standard.

Catching intermediate event:

• Only boundary version exists.

Throwing intermediate event:
In normal flow, the Compensation Intermediate Event raises a compensation.

• Name:
• Documentation:
• ActivityReference:
  Points to the activity to which to compensate.

End event:

• Name:
• Documentation:
• ActivityReference:
  Points to the activity or event sub-process to which to compensate.