ORM. Создание сущности наследницы класса UserTable

class SkidkaUserTable extends Main\UserTable
{
    public static function getMap()
    {
        $result = parent::getMap();
        $result = array_merge($result, array(
            'UF_CATEGORY_ID' => array(
                'data_type' => 'string',
                'title' => 'Привязка к категориям'
            )
        ));
        return $result;
    }
    public static function GetList($arParams = array()){
        if (isset($arParams['arNavParams'])) {
            $arPagerParams = array();
            $obCDBResult = new \CDBResult();
            $arNavParams = $arParams['arNavParams'];
            unset($arParams['arNavParams']);
            if ($arNavParams['nPageSize']) {
                $arPagerTmp = $obCDBResult->GetNavParams($arNavParams);
                $obPagerQuery = new \Bitrix\Main\Entity\Query(__CLASS__);
                $obPagerQuery->SetSelect(array('ID'));

                if ($arParams['filter']) {
                    $obPagerQuery->SetFilter($arParams['filter']);
                }
                if ($arParams['group']) {
                    $obPagerQuery->SetGroup($arParams['group']);
                }

                $dbItems = $obPagerQuery->Exec();
                $arPagerParams['NavPageSize'] = intval($arNavParams['nPageSize']);
                $arPagerParams['NavPageSize'] = $arPagerParams['NavPageSize'] > 0 ? $arPagerParams['NavPageSize'] : 10;
                $arPagerParams['NavRecordCount'] = $dbItems->GetSelectedRowsCount();
                $arPagerParams['NavPageNomer'] = $arPagerTmp['PAGEN'];
                $arPagerParams['NavPageCount'] = ceil($arPagerParams['NavRecordCount'] / $arPagerParams['NavPageSize']);

                $arParams['limit'] = $arPagerParams['NavPageSize'];
                $arParams['offset'] = ($arPagerParams['NavPageNomer'] - 1) * $arPagerParams['NavPageSize'];
            } elseif ($arNavParams['nTopCount']) {
                $arParams['limit'] = intval($arNavParams['nTopCount']);
                $arParams['limit'] = $arParams['limit'] > 0 ? $arParams['limit'] : 10;
            }
        }
        $obResult = parent::GetList($arParams);

        if ($arPagerParams) {
            $obResult->bNavStart = false;
            $obResult->NavRecordCount = $arPagerParams['NavRecordCount'];
            $obResult->NavPageCount = $arPagerParams['NavPageCount'];
            $obResult->NavPageNomer = $arPagerParams['NavPageNomer'];
            $obResult->NextPageNomer = (($bpn = $obResult->NavPageNomer + 1) <= $obResult->NavPageCount) ? $bpn : false;
            $obResult->PrevPageNomer = (($ppn = $obResult->NavPageNomer - 1) > 0) ? $ppn : false;
        }
        return $obResult;
    }
}