toJson method
Implementation
@override
Map<String, Object?> toJson() => {
if (product != null) "product": encodeValue(product),
if (productId != null) "product_id": encodeValue(productId),
if (price != null) "price": encodeValue(price),
if (priceId != null) "price_id": encodeValue(priceId),
if (usage != null) "usage": encodeValue(usage),
if (expiresAt != null) "expires_at": encodeValue(expiresAt),
if (presentation != null) "presentation": encodeValue(presentation),
"quantity": encodeValue(quantity),
};