GH-3425: Return modified map from AnnotationEnhancer

Fixes: #3425

Implement fix for issue #3425 by modifying AnnotationEnhancer to return
the updated map after processing. This change ensures that all
annotation enhancements are properly reflected in the returned result.

Modifying an existing test to verify this behavior.

Author: sobychacko

spring-kafka/src/main/java/org/springframework/kafka/annotation/KafkaListenerAnnotationBeanPostProcessor.java

@@ -142,6 +142,7 @@
  * @author Tomaz Fernandes
  * @author Wang Zhiyang
  * @author Sanghyeok An
+ * @author Soby Chacko
  *
  * @see KafkaListener
  * @see KafkaListenerErrorHandler
@@ -360,7 +361,7 @@ private void buildEnhancer() {
 					for (AnnotationEnhancer enh : enhancers) {
 						newAttrs = enh.apply(newAttrs, element);
 					}
-					return attrs;
+					return newAttrs;
 				};
 			}
 		}

spring-kafka/src/test/java/org/springframework/kafka/annotation/AliasPropertiesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2023 the original author or authors.
+ * Copyright 2018-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,7 @@
 import java.lang.annotation.Target;
 import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Method;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -56,6 +57,7 @@
 /**
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Soby Chacko
  *
  * @since 2.2
  *
@@ -113,13 +115,15 @@ public static class Config {
 
 		@Bean
 		public static AnnotationEnhancer mainEnhancer() {
+
 			return (attrs, element) -> {
-				attrs.put("groupId", attrs.get("id") + "." + (element instanceof Class
+				Map<String, Object> newAttrs = new HashMap<>(attrs);
+				newAttrs.put("groupId", attrs.get("id") + "." + (element instanceof Class
 						? ((Class<?>) element).getSimpleName()
 						: ((Method) element).getDeclaringClass().getSimpleName()
 								+  "." + ((Method) element).getName()));
 				orderedCalledFirst.set(true);
-				return attrs;
+				return newAttrs;
 			};
 		}