correlationKey does not get loaded when there is no collaboration

[burnettk]

to repro in bpmn-js-spiffworkflow:

1. create an xml file with a correlationKey and no collaboration
2. open the xml file
3. download the file
4. the correlationKey node is gone

it is the same in spiff-arena, though if you add the element back after it is loaded by bpmn js (like by saving in the message editor), it will, in fact, be saved, since the issue manifests at load time, not download time.

[jasquat]

Possible fixes would include:

1. add a phantom collaboration if needed - this will not display on the diagram but will be in the xml
2. add support for correlation keys at the root of a process using moddle exentions
3. don't add any correlation keys ever

[burnettk]

we discussed attempting option 1, and seeing if it seems to work, including for the use case where you later want to use the editor to actually create a collaboration that is visible on the diagram.

we believe that adding correlationKey nodes outside a collaboration node would result in invalid bpmn xml, so that is a point against option 2.

[jasquat]

Adding the collaboration tag in the xml does indeed not display in the diagram and bpmn-js does not remove it on save. When a new collaboration is added, bpmn-js does add a whole new collaboration which may not be a problem really.

However, it seems like there is still another issue with this approach. It seems like the correlation key is not being used on the receive side. Even when it has the MainCorrelationKey, the message name is still being used for correlation key name.