purchaseOrderNumber = $purchaseOrderNumber; $this->encodedLabelData = $encodedLabelData; $this->labelFormat = $labelFormat; } public function getTrackingNumber(): string { return $this->trackingNumber; } public function setTrackingNumber(string $trackingNumber): self { $this->trackingNumber = $trackingNumber; return $this; } public function hasTrackingNumber(): bool { return $this->trackingNumber !== null; } public function getEncodedLabelData(): string { return $this->encodedLabelData; } public function jsonSerialize(): array { return [ 'purchase_order_number' => $this->purchaseOrderNumber, 'tracking_number' => $this->trackingNumber, 'encodedLabelData' => $this->encodedLabelData ]; } }