public function addAttributeValues(Entry $entry, string $attribute, array $values)
    {
        $con = $this->getConnectionResource();

        if (!@ldap_mod_add($con, $entry->getDn(), [$attribute => $values])) {
            throw new LdapException(sprintf('Could not add values to entry "%s", attribute %s: %s.', $entry->getDn(), $attribute, ldap_error($con)));
        }
    }