Simplify WebApplicationContext class guard

See gh-3856

spring-boot-samples/spring-boot-sample-simple/src/main/java/sample/simple/SampleSimpleApplication.java

@@ -20,6 +20,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
 import sample.simple.service.HelloWorldService;
 
@@ -39,6 +40,9 @@ public class SampleSimpleApplication implements CommandLineRunner {
 	}
 
 	public static void main(String[] args) throws Exception {
+		SpringApplication application = new SpringApplication(
+				SampleSimpleApplication.class);
+		application.setApplicationContextClass(AnnotationConfigApplicationContext.class);
 		SpringApplication.run(SampleSimpleApplication.class, args);
 	}
 }