SystemField::getByUserFieldName

static function getByUserFieldName(string $fieldName): ?string
{
	$fieldList = self::getBuildedFieldList();
	if (empty($fieldList))
	{
		return null;
	}

	$result = null;
	foreach ($fieldList as $field)
	{
		$baseParams = $field::getUserFieldBaseParam();
		if ($baseParams['FIELD_NAME'] === $fieldName)
		{
			/** @var string $result */
			$result = $field;
			break;
		}
	}
	unset($baseParams, $field, $fieldList);

	return $result;
}