The impersonation token endpoints have been re-worked and made available to all CSP (it was a google only technology). A new set of endpoints have been created and the old endpoints (/imptoken) have been marked as obsolete in the documentation.
The impersonation token is now generated by the auth provider specified in the authorization abstraction layer (each CSP can use its own auth provider)
The impersonation token can be generated/refreshed/retired only by a trusted application
