CUserTypeManager::isValueEmpty

protected function isValueEmpty(array $userField, $value): bool
{
	$className = $userField['USER_TYPE']['CLASS_NAME'] ?? null;
	if (!is_a($className, BaseType::class, true))
	{
		$className = BaseType::class;
	}
	if (!$className::isMandatorySupported())
	{
		return false;
	}
	$isNumberType = (
		$userField['USER_TYPE_ID'] === BitrixMainUserFieldTypesIntegerType::USER_TYPE_ID
		|| $userField['USER_TYPE_ID'] === BitrixMainUserFieldTypesDoubleType::USER_TYPE_ID
	);
	if (
		$isNumberType
		&& (
			$value === 0 || $value === 0.0 || $value === "0" || $value === "0.0" || $value === "0,0"
		)
	)
	{
		return false;
	}

	return (string)$value === "";
}