Update concrete syntax of attached associations

* Load the SimpleClassDiagram toolbar
* Create two classes
* Create a 'test' association between the two classes
* On the head of the association, edit the class
* Put the following in the cardinalities section and hit ok
```
{
{
"dir": "in",
"type": "test",
"min": "0",
"max": "1"
}
}
```
* Note that the cardinality is not updated visually

Start by reproducing the issue through the SimpleClassDiagram toolbar: create two classes, add a test association, and edit its head cardinalities with the provided JSON. Trace the association editor and visual update path; done means the entered cardinality is displayed after confirming the edit.

Written by the indexing model from the issue text.