See https://developer.paypal.com/docs/api/orders/v2/#definition-order.
Creates an order object using constructor.
Adds a new purchase unit item into purchase_units array.
Gets an array for purchase units from an order.
Sets the application context of an order.
Gets an order application context.
Sets an order intent.
Gets an order intent.
Gets an order id.
Gets an order status.
Gets an order payee.