In Spring MVC, the request lands on DispatcherServlet. DispatcherServlet can be declared in web.xml or as a Java configuration if your servlet container is 3.0+. Please create a dummy SpringSecurityConfig.java file. We will be constructing this class when we explain the first authentication mechanism, namely, basic authentication:

public class SpringMvcWebApplicationInitializer
       extends AbstractAnnotationConfigDispatcherServletInitializer {

   @Override
   protected Class<?>[] getRootConfigClasses() {
       return new Class[] { ApplicationConfig.class, SpringSecurityConfig.class };
   }

   @Override
   protected Class<?>[] getServletConfigClasses() {
       return new Class[] { WebApplicationConfig.class };
   }

   @Override
   protected String[] getServletMappings() {
       return new String[] { "/" };
   }

}