FreePBX LDAP authentication should accept alternative RDNs

We run FreePBX 14.0.13.40 and users are being synchronised from OpenLDAP server. This works flawlessly.
In order to let the users log in to the UCP I tried to make the LDAP authentication work but I learned that FreePBX insists on the LDAP RDN cn as user name. If the user RDN is uid, mail or sth. else, the authentication will never succeed.
My question is if a newer FreePBX version than ours supports alternative RDNs (I would need mail, as our user accounts’ DNs look like this: mail=firstname.lastname@mycompany.com,ou=Users,[domainName=mycompany.com|http://domainname=mycompany.com/],o=domains,dc=mycompany,dc=com
If the latest stable FreePBX version still is restricted to cn , are the FreePBX makers aware of this issue and is it planned to be fixed?