public function setSortBy(?string $sortBy)
    {
        $this->sortBy = $sortBy;
        $this->_sortBy = null !== $sortBy;

        return $this;
    }
public function setSortBy(?string $sortBy)
    {
        $this->sortBy = $sortBy;
        $this->_sortBy = null !== $sortBy;

        return $this;
    }
public function setSortBy ( ? string $ sortBy ) { $ this -> sortBy = $ sortBy ; $ this -> _sortBy = null !== $ sortBy ; return $ this ; }
Set sort by

@param string $sortBy
@return object
Set sort by