Hello! I have pretty simple schema with caveates:

caveat prefix/is_admin(current_role_name string) {
    current_role_name == "Administrator"
}

caveat prefix/is_privileged_user(is_privileged bool) {
    is_privileged
}

definition prefix/role {
    relation admin: prefix/user with prefix/is_admin
    relation privileged_user: prefix/user with prefix/is_privileged_user
    
    permission can_create_documents = admin & privileged_user
}

definition prefix/user {}

When I try to add relationship

prefix/role:adm privileged_user prefix/user:qwerty

with caveat

'prefix/is_privileged_user:{"is_privileged": true}'

I get error "subjects of type

prefix/user

are not allowed on relation `prefix/role#privileged_user`" Please, let me know what do I do wrong?