As a convenience, @Configuration classses may extend ConfigurationSupport, primarily in order to facilitate easy lookup of beans from the enclosing ApplicationContext.

@Configuration
public class AppConfig extends ConfigurationSupport {
    @Bean
    public Service serviceA() {
         // referencing a bean of type DataSource declared elsewhere
        DataSource dataSource = this.getBean(DataSource.class);
        return new ServiceImpl(dataSource);
    }
}