Field::addSaveDataModifier

public function addSaveDataModifier($modifier)
{
	// append only when not null. and when is null - delay it
	if ($this->saveDataModifiers === null)
	{
		$this->additionalSaveDataModifiers[] = $modifier;
	}
	else
	{
		$this->appendSaveDataModifier($modifier);
	}

	return $this;
}