Sub process doesn't render dotted lines despite that they exist in the XML file.

[3ronco]

Although rather uncommon we use a subprocess node with the ability to give 'documents' or 'parameters' to them via a DataObjectReference node. Earlier versions showed these flows as a dotted line among a document and a subprocess.
The recent version doesn't render these arrows anymore although they can be found as shape nodes in the XML file. It's not happening with earlier versions eg. V8.7.1

Reproduce

1. Goto https://demo.bpmn.io/new
2. Append task to start event (optionally give it some name)
3. Switch task to type Sub Process (collapsed).
4. Drag a new DataObjectReference above the sub process.
5. Wire DataObjectReference with (dotted arrow) flow to sub process.
6. Drag a new DataObjectReference below the sub process.
7. Wire the sub process with a outgoing flow to the DataObjectReference below.
8. Click "Download as BPMN 2.0 file" ...
9. Create a new tab ... https://demo.bpmn.io/new
10. Click "Open BPMN diagram file from local file system" and select the previously downloaded file.
11. The file loads but without dotted arrows among DataObjectReference nodes and sub processes (and only among these types!)

Expected Behavior
The recently opened diagram file renders exactly the same way as it was when modeled.

Environment

• Browser: Firefox 97.0.2
• OS: Windows 10
• Library version: most recent

[marstamm]

Hi @3ronco ,

thank you for reporting this bug. I was able to reproduce and verify the bug.

Root Cause

The dataInput and dataOutput associations are children of the Activity, where sequence flows are part of the Process.

related BPMN Spec:

With bpmn-js@9, we move all children of subprocesses into the subprocess plane.

bpmn-js/lib/features/drilldown/SubprocessCompatibility.js

Lines 82 to 86 in bdf9cf3

	if (is(parent, 'bpmn:SubProcess') && parent !== plane.bpmnElement) {
	// don't change the array while we iterate over it
	elementsToMove.push({ diElement: diElement, parent: parent });
	}

We did not account for this edge-case, where the element is a child of the subprocess but displayed on root.

Fix

Add a check for edge-cases to the code above to ensure we don't move the data associations into the wrong plane