Spring Boot: @SpringBootApplication is three annotations in one

@SpringBootApplication
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

// Equivalent to:
@Configuration
@EnableAutoConfiguration
@ComponentScan
public class App { }

Component scanning starts at the class's own package.
A @Service in a sibling package is never found - a classic "bean not created" cause.