Information about the customer collected within the Checkout Session. Can only be set when updating `embedded` or `custom` sessions.

Specifies which fields in the response should be expanded.

A list of items the customer is purchasing. When updating line items, you must retransmit the entire array of line items. To retain an existing line item, specify its `id`. To update an existing line item, specify its `id` along with the new values of the fields to update. To add a new line item, specify one of `price` or `price_data` and `quantity`. To remove an existing line item, omit the line item's ID from the retransmitted array. To reorder a line item, specify it at the desired position in the retransmitted array.

Set of [key-value pairs](https://docs.stripe.com/api/metadata) that you can attach to an object. This can be useful for storing additional information about the object in a structured format. Individual keys can be unset by posting an empty value to them. All keys can be unset by posting an empty value to `metadata`.

The shipping rate options to apply to this Session. Up to a maximum of 5.