private function changed()
{
if ( ! $this->isDirty) {
$this->isDirty = true;
if ($this->dm && $this->mapping !== null && $this->dm->getClassMetadata(get_class($this->owner))->isChangeTrackingNotify()) {
$this->dm->getUnitOfWork()->scheduleForDirtyCheck($this->owner);
}
}
}