We can now proceed with the design phase of the entities we need for this implementation. Let's start with the Item class, which will be the central entity in our domain model. It is a representation of a music album, and it contains all the attributes and characteristics related to albums, including the description, name, release date, and format. The entity will also provide some additional information that is usually present in a catalog, such as available stock, a picture, and the price.

Let's start by designing a diagram to describe our code:

This diagram defines the entities involved in the service:

• Item is the primary entity in our claim. It contains all the information about the album and the references to the artist and the genre.
• The Artist entity represents the artist associated with the album.
• The Genre entity represents the music genre associated with the album.
• The Money entity represents the price of the album. This is a complex type that contains the amount of money and the currency it is in.