Optionalprevious_Object containing the names of the updated attributes and their values prior to the event (only included in events of type *.updated). If an array attribute has any updated elements, this object contains the entire array. In Stripe API versions 2017-04-06 or earlier, an updated array attribute in this object includes only the updated array elements.
Object containing the API resource relevant to the event. For example, an
invoice.createdevent will have a full invoice object as the value of the object key.