Monitor::getOwnerAssignedBy

private function getOwnerAssignedBy(ItemIdentifier $timelineOwner): int
{
	$factory = Container::getInstance()->getFactory($timelineOwner->getEntityTypeId());
	if (!$factory)
	{
		return 0;
	}
	if (!$factory->isFieldExists(\Bitrix\Crm\Item::FIELD_NAME_ASSIGNED))
	{
		return 0;
	}

	$assignedByFieldName = $factory->getEntityFieldNameByMap(\Bitrix\Crm\Item::FIELD_NAME_ASSIGNED);

	return $factory->getDataClass()::getList([
			'filter' => [
				'=ID' => $timelineOwner->getEntityId(),
			],
			'select' => [
				$assignedByFieldName,
			],
			'limit' => 1,
		])->fetch()[$assignedByFieldName] ?? 0
	;
}