The API diagram displays the involved application entities and their relations to domain entities.
The Car application entity extends the eponymous domain entity to enrich it with rental information.
The Customer application entity represents a person authorized to rent cars. It only consists of its identifier.
The Rental application entity contains the time period during which a customer rents a car. The 'active' indicator is derived from this period and the current timestamp.
The TrunkAccessToken application entity is a token that expresses a person's permission to open the trunk of the car while the corresponding rental is active.