Script Mapper not working, injected vars are undefined

Configuring the server
1

Hello there,
I wanted to include role attributes in JWT token, which apparently is not possible out of the box: only user attributes can be mapped. I discovered that custom Script Mapper can be the solution.
I managed to configure Keycloak so that I can type in the JavaScript code.

Sadly, the example I found didn’t work. Then I realized that all variables like user, token are undefined.

Here is my sample code of mapper I wrote to debug what’s happening:

/**
 * Available variables: 
 * user - the current user
 * realm - the current realm
 * token - the current token
 * userSession - the current userSession
 * keycloakSession - the current keycloakSession
 */


//insert your code here...

var ret = [];
ret.push('Hello');
ret.push(user);
ret.push(realm);
ret.push(token);
ret.push(userSession);
ret.push(keycloakSession);

JSON.stringify(ret);

And the token claim shows something like this (look for x_userid claim):

{
  "exp": 1598069388,
  "iat": 1598040588,
  "jti": "aefbbb2e-adae-4513-b9cd-531c203c4768",
  "iss": "http://localhost:9002/auth/realms/hotel",
  "aud": "account",
  "sub": "9811c27a-f1de-4efa-ab9a-eb53ef29dc4f",
  "typ": "Bearer",
  "azp": "hotel-ui-react-dev",
  "session_state": "5d6d7e9d-52e5-4ef4-a8c7-759f611ee37e",
  "acr": "1",
  "allowed-origins": [
    "http://localhost:3000"
  ],
  "realm_access": {
    "roles": [
      "hotelier",
      "offline_access",
      "uma_authorization"
    ]
  },
  "resource_access": {
    "account": {
      "roles": [
        "manage-account",
        "manage-account-links",
        "view-profile"
      ]
    }
  },
  "scope": "openid profile email",
  "email_verified": true,
  "x_userid": [
    "Hello",
    null,
    null,
    null,
    null,
    null
  ],
  "preferred_username": "hotel"
}

So definitely the mapper is working, the result appears in JWT token, but since all injected variables are null, code won’t work.

I tried it both via JS client adapter in React app, via Postman and even using obscure “evaluate” function in client settings in admin. Same result everywhere.

I was working on 10.0.2 but started 11.0.1 version (all in Docker) to no avail. Did I miss something?