Improve deprecated exception message

Update the exception message so that it includes the class name of the
implementation.

See gh-22497

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java

@@ -192,8 +192,8 @@ public class ConfigFileApplicationListener implements EnvironmentPostProcessor,
 
 	@Override
 	public void onApplicationEvent(ApplicationEvent event) {
-		throw new IllegalStateException(
-				"ConfigFileApplicationListener is deprecated and can only be used as an EnvironmentPostProcessor");
+		throw new IllegalStateException("ConfigFileApplicationListener [" + getClass().getName()
+				+ "] is deprecated and can only be used as an EnvironmentPostProcessor");
 	}
 
 	@Override