Cart constructor
      
      Cart({ 
    
    
- String? cartId,
 - String? intent,
 - List<
Items> ? items, - UnitPrice? total,
 - List<
ShippingMethod> ? shippingMethods, - ShippingAddress? shippingAddress,
 - ShippingAddress? billingAddress,
 - UnitPrice? totalAllowedOverCaptureAmount,
 
Implementation
Cart({
  this.cartId,
  this.intent,
  this.items,
  this.total,
  this.shippingMethods,
  this.shippingAddress,
  this.billingAddress,
  this.totalAllowedOverCaptureAmount,
});