ItemFieldsCaster::externalizeFieldId

private function externalizeFieldId(string $fieldId): string
{
	$map = [
		'OBSERVER_IDS' => Crm\Item::FIELD_NAME_OBSERVERS,
		'PRODUCT_IDS' => Crm\Item::FIELD_NAME_PRODUCTS,
	];

	if ($fieldId === Crm\Item::FIELD_NAME_CONTACTS)
	{
		return 'CONTACT_IDS';
	}

	return array_key_exists($fieldId, $map) ? $map[$fieldId] : $fieldId;
}