fix: fix allowedIn for zeebe:LoopCharacteristics

[philippfromme]

zeebe:LoopCharacteristics isn't restricted to certain flow elements but to bpmn:MultiInstanceLoopCharacteristics. This is also how it's validated by the engine.

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Related to camunda/camunda-modeler#4310

[nikku]

@philippfromme And we do read the "allowedIn" from nested elements? Otherwise this will now break. To date only diagram elements (their business object types) are in allowedElements, cf. check.

[barmac]

If I understand this correctly, the copyPasteBehavior checks the ancestor elements regardless if they are flow elements or not, cf. https://github.com/camunda/camunda-bpmn-js-behaviors/blob/main/lib/camunda-cloud/CopyPasteBehavior.js#L84
What I'd suggest though is to have an accompanying pull request on camunda-bpmn-js-behaviors to verify the fix in an integration test.

[nikku]

Thanks @barmac for the context. Looks good to me then. ✔️

[philippfromme]

Integration test: camunda/camunda-bpmn-js-behaviors#84