More sensible signature for servlet initializer

spring-boot-samples/spring-boot-sample-websocket/src/main/java/org/springframework/boot/samples/websocket/config/SampleWebSocketsApplication.java

@@ -36,8 +36,8 @@ import org.springframework.web.socket.support.PerConnectionWebSocketHandler;
 public class SampleWebSocketsApplication extends SpringBootServletInitializer {
 
 	@Override
-	protected void configure(SpringApplicationBuilder application) {
-        application.sources(SampleWebSocketsApplication.class);
+	protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
+        return application.sources(SampleWebSocketsApplication.class);
     }
 
 	public static void main(String[] args) {

spring-boot/src/main/java/org/springframework/boot/web/SpringBootServletInitializer.java

@@ -86,7 +86,7 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 		application.initializers(new ServletContextApplicationContextInitializer(
 				servletContext));
 		application.contextClass(AnnotationConfigEmbeddedWebApplicationContext.class);
-		configure(application);
+		application = configure(application);
 		return (WebApplicationContext) application.run();
 	}
 
@@ -99,7 +99,8 @@ public abstract class SpringBootServletInitializer implements WebApplicationInit
 	 * @param application a builder for the application context
 	 * @see SpringApplicationBuilder
 	 */
-	protected void configure(SpringApplicationBuilder application) {
+	protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
+		return application;
 	}
 
 }