Fix Checkstyle violations

See gh-23784

spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java

@@ -295,9 +295,11 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 	@Nullable
 	protected Object doInvoke(Object... args) {
 		Object bean = getTargetBean();
+		// Detect package-protected NullBean instance through equals(null) check
 		if (bean.equals(null)) {
-		    return null;
+			return null;
 		}
+
 		ReflectionUtils.makeAccessible(this.method);
 		try {
 			return this.method.invoke(bean, args);

spring-context/src/test/java/org/springframework/context/event/AnnotationDrivenEventListenerTests.java

@@ -16,8 +16,6 @@
 
 package org.springframework.context.event;
 
-import java.io.Closeable;
-import java.io.IOException;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -627,12 +625,13 @@ public class AnnotationDrivenEventListenerTests {
 	}
 
 	@Test
-	public void missingBeanDoesntCrash() {
-	    load(MissingEventListener.class);
-	    context.getBean(UseMissingEventListener.class);
-	    context.getBean(ApplicationEventMulticaster.class).multicastEvent(new TestEvent(this));
+	public void missingListenerBeanIgnored() {
+		load(MissingEventListener.class);
+		context.getBean(UseMissingEventListener.class);
+		context.getBean(ApplicationEventMulticaster.class).multicastEvent(new TestEvent(this));
 	}
 
+
 	private void load(Class<?>... classes) {
 		List<Class<?>> allClasses = new ArrayList<>();
 		allClasses.add(BasicConfiguration.class);
@@ -1087,31 +1086,32 @@ public class AnnotationDrivenEventListenerTests {
 	}
 
 	@Configuration
-	@Import({UseMissingEventListener.class})
+	@Import(UseMissingEventListener.class)
 	public static class MissingEventListener {
-	    @Bean
-	    public MyEventListener missing() {
-	        return null;
-	    }
+
+		@Bean
+		public MyEventListener missing() {
+			return null;
+		}
 	}
 
 	@Component
-	public static class MyEventListener implements Closeable {
-	    @EventListener
-	    public void hear(TestEvent e) {
-	        throw new AssertionError();
-	    }
+	public static class MyEventListener {
 
-	    @Override
-	    public void close() throws IOException {}
+		@EventListener
+		public void hear(TestEvent e) {
+			throw new AssertionError();
+		}
 	}
 
 	public static class UseMissingEventListener {
-	    @Inject
-	    public UseMissingEventListener(Optional<MyEventListener> notHere) {
-	        if (notHere.isPresent()) {
-	            throw new AssertionError();
-	        }
-	    }
+
+		@Inject
+		public UseMissingEventListener(Optional<MyEventListener> notHere) {
+			if (notHere.isPresent()) {
+				throw new AssertionError();
+			}
+		}
 	}
+
 }