What API attribute should be used to retrieve linked objects like the Checkout Session and Customer object in a single call?

To retrieve linked objects such as the Checkout Session and Customer object in a single API call, the correct approach is to use the expand fields attribute. This attribute allows developers to specify which related objects or nested resources they want to include in the response when making a request to the Stripe API.

When you apply the expand fields feature, the API will not only return the primary resource you requested but also include the specified related objects. For example, if you expand the Customer object while creating or retrieving a Checkout Session, the response will contain detailed information about that Customer along with the Checkout Session data, reducing the number of API calls required to gather comprehensive information about related resources.

This feature streamlines the process for developers, as they can access all necessary data in one response, improving efficiency and performance by minimizing multiple round-trips to the server. The use of expand fields is a powerful tool for building applications that require a rich understanding of how various Stripe resources are interlinked, ultimately leading to a better integration experience.