How to post to google plus via google domain api?

Question

Google Plus

When trying to call methods

plusDomains.activities.list

or

plusDomains.activity.insert

api explorer returns 403 even though I'm calling super-admin methods on MyBusiness Google+ Page (owner's account).
Also returns 403 when posting from a web application.
google api explorer error text:

403 Forbidden
- Show headers -
{
 "error": {
  "errors": [
   {
    "domain": "plusDomains",
    "reason": "forbiddenScope",
    "message": "Access to the Google+ Domains API is not allowed as the user has consented to incompatible scopes. See: https://developers.google.com/+/domains/authentication/."
   }
  ],
  "code": 403,
  "message": "Access to the Google+ Domains API is not allowed as the user has consented to incompatible scopes. See: https://developers.google.com/+/domains/authentication/."
 }
}

UPD: stackoverflow.com/questions/31912197/google-domain...