[keycloak-user] Access Token - compatibility

Hi all I'm looking at the future of our architecture, including how we secure APIs (Resource Servers) and more. It is important that any authorisation services we provide have versioned and 'managed' endpoint interfaces, such that compatibility is maintained across the lifecycle of the authorisation service (patches and upgrades). Since our Resource Servers could be 'anything', we can't rely upon handing out particular libraries for those resource servers to use to integrate with the AS - that would be awful to manage across a large estate of services anyway. As I see it, I can mandate that Resource Servers use OAuth 2, so many issues go away - but the critical item for maintaining compatibility is the Access Token - when we implement the AS, a key deliverable to our RS partners will be a technical specification of the Access Token. Does a technical specification of the Access Token exist? What is the policy with regards to compatibility of the Access Token across versions/patches of KeyCloak? (I could fall back to the Token Info endpoint - but again, that needs to maintain compatibility across releases) Thanks! Simon