[FEAT] Add support for BPMN data objects

[StefanAmEnde]

Describe the bug
When modelling the data-flow perspective in BPMN you use data objects. Although they are correctly shown in the Camunda Modeler, bpmn-visualization will show warnings in the console like e.g.

bpmn-visualization.esm.js:3023 [bv-parser] Edge json deserialization: unable to find bpmn element with id DataOutputAssociation_0yl0bbm

and doesn't display the data objects nor their associations.

To Reproduce
Steps to reproduce the behavior:

1. Create a bpmn process model containing at least one data-object.
   Example:
   
2. integrate the process model in a web application like so:

const xml = "[the bpmn model xml]"
const bpmnVisualization = new BpmnVisualization({container: 'bpmnContainer', navigation: {enabled: true}})
bpmnVisualization.load(xml)

3. observe that the data object(s) is not displayed and warnings are printed in the console

Expected behavior
I expect that data objects should be displayed.

Screenshots
In camunda modeler:

In bpmn-visualization:

Console:

Desktop (please complete the following information):

• OS: Windows 10
• Browser Chrome Version 117.0.5938.134
• Version 0.41.0

Additional context
I'm using bpmn-visualization in a react application. But the problem should be independent of a specific framework.

[tbouffard]

Hi @StefanAmEnde and thanks for this detailed feedback.
In short, this is the expected behavior for now, and here's why 👇🏿

We document the BPMN elements that bpmn-visualization supports in https://process-analytics.github.io/bpmn-visualization-js/#supported-bpmn-elements and the documentation sources for the latest version are available at https://github.com/process-analytics/bpmn-visualization-js/blob/v0.41.0/docs/users/bpmn-support.adoc.
As you can read, we don't support data objects at the moment, and there are other types of elements we don't support (some events, all "data" related types, ...).
Here's a milestone that refers to some of these elements: https://github.com/process-analytics/bpmn-visualization-js/milestone/7

About the current issue: I've converted it into a feature request and moved it to the milestone mentioned above.

Are all these explanations clear to you?

[StefanAmEnde]

Alright. Thanks for the reply👍

[tbouffard]

To complement my first comment:

• We have no plans to support BPMN data objects in the near future.
• But this doesn't mean we won't do it later
• Our decision may be influenced by the number of people requesting this feature.