role property missing in response of drive item permissions api

Question

https://learn.microsoft.com/en-us/graph/api/driveitem-list-permissions?view=graph-rest-1.0&tabs=http#http-request

I am getting an empty list in 'value' for a folder that is read-only for me. What does that mean?

Here are the steps I followed to access that folder:

1. I am a member of a site.
2. Site owner created a folder.
3. Then, Site owner changed the permission to 'Can view' for the site members.
4. 
5. Then I executed the **GET /drives/{drive-id}/items/{item-id}/permissions **api.
6. I got this:

{
  "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#users('{user-id}')/drives({drive-id}')/items('{item-id}')/permissions",
  "value": []
}