Expression editor : is there any documentation to help to use it ?

Summary:

Looking for documentation or guidance on using the Expression Editor in Oracle HCM Cloud to control button visibility based on user roles.

Content (please ensure you mask any confidential information):

I need to hide the "Add Absence" button only for Managers while keeping it visible for Employees.

The visibility setting offers three options: True, False or Expression Editor.

I need to use the Expression Editor, but I can't find any documentation or examples on how to use it for role-based visibility control.

Has anyone in the community done this before or can share resources? Any help would be appreciated!