Additionally, the mobile app can use this feature to render the whiteboard inside an iframe with the same `userId`.
By setting the parameter `revokePreviousSession=true`, a new `sessionToken` will be generated, and the previous session will be revoked when the new device connects. This is useful for transferring a session to another device and automatically closing the previous session.
* Introduce Gql-Middleware config as a yml file
* use path /usr/share/bbb-graphql-middleware/ instead of /usr/local/bigbluebutton/bbb-graphql-middleware
* remove /etc/default/bbb-graphql-middleware file
