Given this Spring Boot bean code:

Given this Spring Boot bean code:

public class ResourceBean {

    @PostConstruct
    public void setup() {
        System.out.println("Setup resources");
    }

    @PreDestroy
    public void cleanup() {
        System.out.println("Cleanup resources");
    }

    public void start() {
        System.out.println("Start method called");
    }

}

When running the application, the developer notices that "Cleanup resources" is never printed on shutdown. What is the most likely cause?