Automatic user account creation cannot be disabled

[s0rin]

Using MW 1.27.3 & ShibAuthPlugin 1.2.7

Attempted to disable the account creation in using the settings (according to [1])
$wgGroupPermissions['*']['createaccount'] = false;

But using the ShibAuthPlugin 1.2.7 though, anyone logging in using this feature automatically gets a local account created.
Note. The account creation can be disabled when using this setting with the LdapAuthentication 2.1.0 [2] and the option
$wgLDAPDisableAutoCreate = array('testLDAPdomain' => true);.

Another attempt was to change ShibAuthPlugin.php, but it didn't help either:

        function autoCreate() {
                return false;
        }

        function updateExternalDB( $user ) {
                return false;
        }

How to stop the ShibAuthPlugin plugin from automatically creating the accounts?
Does exist an option like $wgLDAPDisableAutoCreate?

[1] https://www.mediawiki.org/wiki/Manual:Preventing_access#Restrict_account_creation
[2] https://www.mediawiki.org/wiki/Extension:LDAP_Authentication