Labels get lost during pool extraction

[nikku]

Describe the Bug

Sometimes users would like to extract the participant contents into a process diagram. If you do that within a single diagram instance the labels get lost:

Steps to Reproduce

• Open example diagram
• Copying the participant contents
• Removing all diagram contents
• Pasting the copied contents
• Diagram is missing labels

Expected Behavior

• Labels are pasted along with elements

Environment

Please complete the following information:

• Browser: Any
• OS: Any
• Library version: v3.0.3

Additional Context

• This is probably due to the quirky label handling during copy/paste (Label is not being pasted diagram-js#206)
• Failing test case reproducing the behavior on feature branch

[pinussilvestrus]

I was able to reproduce this bug on demo.bpmn.io (latest bpmn-js v3.0.3).

[philippfromme]

This is still an issue. Deleting labels unsets their label targets name. The label shape is still copied but won't be visible afterward since the label target has no name. Since we don't serialize business objects when copying we need to copy the name to the descriptor.

[nikku]

Closed via #1151.