tranbaotri2412-star/spring-7-rest-mvc-68-jpa-validation-error-msg

This is a Spring MVC REST example for managing beers and customers. Clients send CRUD requests to the resource controllers, which delegate to service APIs and return DTOs or HTTP status responses. The service layer has in-memory and JPA-backed implementations; the latter maps DTOs to entities and uses Spring Data repositories. Bootstrap data and SQL migrations support initializing and evolving the database. The source index and excerpts establish these components, but do not show how the application selects a service implementation or configures its database.