Spring Boot: Chapter 4 by Brian Clozel, Stephane Nicoll

Brian Clozel and Stéphane Nicoll demonstrate upgrading an application to Spring Boot 4.0, highlighting nullability checks, dependency changes, and Jackson 3.0.

Spring Boot 4.0 is scheduled for next November. While the Java baseline remains at 17, it’s the perfect time to leverage new language and framework features. Stéphane and Brian will start by upgrading their existing application to Spring Boot 4.0.Along the way, we will prevent future NullPointerExceptions in production thanks to Nullness metadata in Spring projects and JSpecify Nullability checks. We will also revisit our application dependency arrangement: Spring Boot now provides fine-grained dependencies that allow for more flexibility in your application. The new Jackson 3.0 integration simplifies our Jackson setup and updates configuration options with more modern opinions. We will also see how we can use a RestClient in asynchronous scenarios without involving Reactive types.