Token simulation allows incoming sequence flows for events after an event based gateway

[marstamm]

Describe the Bug

Reported as camunda/camunda-modeler#3984

When adding token simulation to the modeler, I can model non spec-compliant diagrams, which are not possible without the plugin.

Steps to Reproduce

Try to model the above diagram

Expected Behavior

Environment

• Host (Browser/Node version), if applicable: [e.g. MS Edge 18, Chrome 69, Node 10 LTS]
• OS: [e.g. Windows 7]
• Library version: [e.g. 2.0.0]

[sombrek]

I found that EventBasedGatewayBehavior.js (token-simulation) overrides EventBasedGatewayBehavior.js (bpmn-js). The latter removes sequence flows disallowed by the spec.

[nikku]

This should make it easy for us to fix. Thanks for the root causing.

[sombrek]

I discovered more examples before I noticed your reference to the public API bug.

• The token simulator exposes a BoundaryEventBehavior, so boundary events of receiving tasks are not removed when they become target of an event gateway.
• It also exposes multiple MessageFlowBehavior, so message flows pointing to elements within a pool don't reconnect to a pool that's being collapsed.

Demo

[barmac]

Thanks for reporting. I think we should look into this.