Arbitrary data in the token

In this tut (https://www.ory.sh/run-oauth2-server-open-source-api-security/) in the section on " Performing the OAuth 2.0 Client Credentials Flow" it is stated that:
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You can set arbitrary data in the token, if you want. For more information on this head over to the developer guide.
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I’ve been scanning the docs but can’t find every reference…any pointers?

Check: https://www.ory.sh/docs/guides/master/hydra/3-overview/1-oauth2#user-consent