src/Models/ElementModel.php
public function refreshSections()
    {
        if ($this->id === null) {
            return [];
        }

        $this->fields['IBLOCK_SECTION'] = [];
        $dbSections = static::$bxObject->getElementGroups($this->id, true);
        while ($section = $dbSections->Fetch()) {
            $this->fields['IBLOCK_SECTION'][] = $section;
        }

        $this->sectionsAreFetched = true;

        return $this->fields['IBLOCK_SECTION'];
    }
public function refreshSections()
    {
        if ($this->id === null) {
            return [];
        }

        $this->fields['IBLOCK_SECTION'] = [];
        $dbSections = static::$bxObject->getElementGroups($this->id, true);
        while ($section = $dbSections->Fetch()) {
            $this->fields['IBLOCK_SECTION'][] = $section;
        }

        $this->sectionsAreFetched = true;

        return $this->fields['IBLOCK_SECTION'];
    }
Refresh element's sections and save them to a class field.

@return array