code: public function setNumber($number)
      {
          if (!is_null($number) && (strlen($number) > 120)) {
              throw new \InvalidArgumentException('invalid length for $number when calling OrderShippingTracking., must be smaller than or equal to 120.');
          }
  
          $this->container['number'] = $number;
  
          return $this;
      }
docs: Sets number
  @param string $number
  @return $this