You are writing a Python script that uses RESTCONF to push OSPF configuration to an IOS XE device fronted by an API gateway. The gateway enforces OAuth 2.0 client-credentials flow: you must first POST client_id and client_secret to a /token endpoint, receive a short-lived bearer token, and then include it on every RESTCONF request. The RESTCONF payload is JSON encoded per RFC 8040. Which combination of HTTP headers must your RESTCONF configuration request carry to authenticate and be accepted by the device?