• I used Hexgaonal architecture with Domain Driven Design
• Aggregate roots: Customer and Book
• Value objects: EuroMoney, CustomerId, BookId, LoyaltyPoints, Percentage, BookType's
• I used Joda Money to represent Customer balance and Book price but its wrapped with VO EuroMoney
• Using Swagger, Loggs and Unit tests
• As persistence layer i have H2 Database with Hibernate And Spring JPA
• There could be some refactoring of variable names, maybe even code design but as requirements are not fully defined i had freedom to design simple as possible

How tu run application? Just press run in your favorite IDE, if you want to change data use resource/data-h2.sql file

How to use application? There is 3 endpoints as stated in task

• To get Customer details use localhost:8080/api/v1/customers/{customer-id}
• To get All books details use localhost:8080/api/v1/books
• To create payment use localhost:8080/api/v1/customers/{customer-id}/checkout?booksId={book-id},{book-id}
• Swagger link localhost:8080/swagger-ui.html