src/Entities/Cart.php
public function getItemsByMerchantID($merchantID)
    {
        return array_filter($this->getItems(), function(CartItem $item) use ($merchantID)
        {
            return $item->getProduct()->getOrganisation()->getId() == $merchantID;
        });
    }
public function getItemsByMerchantID($merchantID)
    {
        return array_filter($this->getItems(), function(CartItem $item) use ($merchantID)
        {
            return $item->getProduct()->getOrganisation()->getId() == $merchantID;
        });
    }
@param int $merchantID

@return array