protected function addControlsToString($ldif)
{
foreach ($this->controls as $control) {
$value = $control->getOid() . ' ' . $control->getCriticality();
if (!is_null($control->getValue())) {
$value .= ' ' . $control->getValue();
}
$ldif .= $this->getLdifLine(Ldif::DIRECTIVE_CONTROL, $value);
}
return $ldif;
}