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Note that the Oauth2 specification does not define the format of the tokens, but introduces the Tokensintrospect endpoint for retrieving meta information related to the tokens. OAuth2 considers the tokens opaque to the client.
OpenID Connect on the other hand, defines the basic token format for the ID Token. The ID Token can be extended using custom TokensClaims.
Tokens issued by the Buypass OpenID Provider are described in more detailed here:
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