The _refResourceRev field is missing from VertexEdge Responses.
Create a user that is assigned a role.
Modify the user twice, note that the rev of the user is now 2.
Modify the role once, note that the rev if the role is now 1.
A query like the following should return a `_refResourceRev` field that holds the revision of the role object.
(just FYI - `_refProperties/_rev` is the revision of the relationship, and not that of the referenced object).
Note that if a EdgeVertex request is made, the `_refResourceRev` field is properly returned.