Using primary key objects with Spring Data and Hibernate

Instead of using primitive types like Long or UUID as JPA entity primary keys, you can wrap them in dedicated objects (e.g., UserId, OrderId) for stronger type safety. This requires creating an EntityId interface, a custom IdentifierGenerator that bridges the database-generated long to the wrapper object, and using @EmbeddedId with @GenericGenerator on the entity. The approach prevents accidental parameter mix-ups in service methods and integrates cleanly with Spring Data repositories.