GH-1137 - Add debug log describing selected externalized events.

Original pull request: GH-1135
Signed-off-by: 조상준 <[email protected]>

Author: sangjun121

spring-modulith-events/spring-modulith-events-core/src/main/java/org/springframework/modulith/events/config/EventExternalizationAutoConfiguration.java

@@ -17,6 +17,8 @@
 
 import java.lang.reflect.Method;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
@@ -46,6 +48,7 @@
 @AutoConfiguration
 @AutoConfigureAfter(EventPublicationConfiguration.class)
 public class EventExternalizationAutoConfiguration {
+    private static final Logger LOG = LoggerFactory.getLogger(EventExternalizationAutoConfiguration.class);
 
 	@Bean
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
@@ -60,6 +63,9 @@ static EventExternalizationConfiguration eventExternalizationConfiguration(BeanF
 
 		var packages = AutoConfigurationPackages.get(factory);
 
+        LOG.debug("Initializing event externalization with packages: {}", packages);
+        LOG.debug("Configured filter to select events annotated with @Externalized within the above packages.");
+
 		return EventExternalizationConfiguration.defaults(packages).build();
 	}