public function addOns()
    {
        $addOns = [];

        foreach ($this->transaction->addOns as $addOn) {
            $addOns[] = $addOn->id;
        }

        return $addOns;
    }
public function addOns()
    {
        $addOns = [];

        foreach ($this->transaction->addOns as $addOn) {
            $addOns[] = $addOn->id;
        }

        return $addOns;
    }
public function addOns ( ) { $ addOns = [ ] ; foreach ( $ this -> transaction -> addOns as $ addOn ) { $ addOns [ ] = $ addOn -> id ; } return $ addOns ; }
Get the add-on codes applied to the invoice.

@return array
Get the add - on codes applied to the invoice .