Non Interactive Client on Enduser server - how to auth?

It is all clear how to authorize Non Interactive Client (NIC) which is running on our backend server - use Client Credentials Grant.
But we have third party NIC running on end user’s backend. Since it is NIC, there is no user who can authenticate. So we can’t use Implicit Grant or any other similar grant.
We cannot use Client Credentials Grant because it does not contain any information about enduser (id_token) and we do not want to enable access to all data on our Resource Server.

So, how should we proper authenticate NIC on enduser side?


As it has been more than a few months since this topic was opened, and there has been no reply or further information provided as to the existence of the issue, we are closing this topic. Please don’t hesitate to create a new topic if this issue is still present, we would be happy to work with you to help find a resolution.