See
- [Custom Attributes](https://gluu.org/docs/customize/attributes/)
- [Automating Custom Attribute Configuration](https://gluu.org/docs/how-to/automate-schema/)
- [Schema Auto-generated docs](https://gluu.org/docs/gluu-defaults/schema/)
Note: by default, the objectclass is `gluuPerson` which may contain role. Check the objectclass in the gluu schema file located in the folder `/opt/opendj/config/schema`
Grep for role and you'll probably turn it up.
Also, don't forget that there is LDAP schema, but there is also an LDAP entry for each attribute in your Gluu Server configuration under `ou=attributes,o=org-inum,o=gluu`