How to add custom fields not existing in User to JWT token and populate values?

if I need a custom fields in JWT token how can I add them and fill them up

see docs: https://casdoor.org/docs/application/terminology#:~:text=empty%20values)%20or-,JWT%2DCustom,-customizing%20User%20fields

But I wanted to add the field that don't exist in User. I could see that I can add other nonfields like workspace and all in Token Fields but how do I populate it with the values, is there any kind of mapper like the one exists in keycloak

My scenario here is I have a abstraction UI call Workspace where the user perform various tasks. A user can be a admin/member of the workspace and a user can have multiple workspace where he/she could be a admin in one and member in other. How could I handle such using Casdoor and give a restrictive view when user login?

I see that in User table we have a field call properties, so during a sign up how can I map certain fields and its value to it? Please your help is fully appreciated . I am new to GO and Casdoor.

casdoor has a lot of fields, re-use them, just strings

if UI needs change, modify code