Do we allow unresolved annotation instances?

[enikao]

We DO allow unresolved references (referenceTargetId below) and DO NOT allow unresolved containments (childId).
How about unresolved annotation instances (annotationInstanceId)?

{
  "id": "myNode",
  "classifier": ...,
  "properties": [],
  "containments": [
    {
      "containment": ...,
      "children": [
        "childId"
      ]
    }
  ],
  "references": [
    {
      "reference": ...,
      "targets": [
        "referenceTargetId"
      ]
    }
  ],
  "annotations": [
    "annotationInstanceId"
  ],
  "parent": null
}

Pro (allow unresolved annotation instances):

• Annotations are meant as auxiliary, not really needed for the (core) model

Con:

• Structurally, they are very close to containments, so they should follow the same rules

[joswarmer]

For references we have both a referred id, as well as a resolveInfo, so there are more options to rebind a reference. For annotations we only have an id, as with containments. This would argue for not allowing unresolved annotations.

However, a model is structurally correct, no matter annotations, so it would be easy to ignore unresolved annotations.