gistfile1.php

<?php

        $oid = new ObjectIdentity('class', $this->threadClass);
        $sid = UserSecurityIdentity::fromAccount($this->securityContext->getToken()->getUser());
        foreach ($this->aclProvider->findAcl($oid)->getClassAces() AS $entry) {
            if ($entry->getSecurityIdentity()->equals($sid)) {
                var_dump($entry->getMask()); // Doesnt dump, The user has role ROLE_SUPERADMIN
            }
        }

        $oid = new ObjectIdentity('class', $this->threadClass);
        $sid = RoleSecurityIdentity('ROLE_SUPERADMIN');
        foreach ($this->aclProvider->findAcl($oid)->getClassAces() AS $entry) {
            if ($entry->getSecurityIdentity()->equals($sid)) {
                var_dump($entry->getMask()); // Dumps
            }
        }