Springboot Patterns

This covers the bread and butter patterns you'll use building Spring Boot APIs: proper controller-service-repository layering, JPA repositories with custom queries, request/response DTOs with validation, global exception handling, and caching with eviction. It includes practical async processing, structured logging with correlation IDs, and pagination patterns. The rate limiting example is thorough about the security implications of using forwarded headers behind proxies. Good for mid-level developers who know Spring basics but want to see how the pieces fit together in production code, especially around error handling and non-functional requirements like caching and monitoring.