public function setInventory_number($inventory_number = null)
{
// validation for constraint: string
if (!is_null($inventory_number) && !is_string($inventory_number)) {
throw new \InvalidArgumentException(sprintf('Invalid value, please provide a string, "%s" given', gettype($inventory_number)), __LINE__);
}
$this->inventory_number = $inventory_number;
return $this;
}