DefaultMessagePropertiesConverter: improve conditions

We can reduce `else if` condition in method `DefaultMessagePropertiesConverter.convertLongStringIfNecessary()`

Author: ngocnhan-tran1996

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/support/DefaultMessagePropertiesConverter.java

@@ -42,6 +42,7 @@
  * @author Soeren Unruh
  * @author Raylax Grey
  * @author Artem Bilan
+ * @author Ngoc Nhan
  *
  * @since 1.0
  */
@@ -275,27 +276,24 @@ private Object convertLongString(LongString longString, String charset) {
 	 * @return the converted string.
 	 */
 	private Object convertLongStringIfNecessary(Object valueArg, String charset) {
-		Object value = valueArg;
-		if (value instanceof LongString longStr) {
-			value = convertLongString(longStr, charset);
+		if (valueArg instanceof LongString longStr) {
+			return convertLongString(longStr, charset);
 		}
-		else if (value instanceof List<?>) {
-			List<Object> convertedList = new ArrayList<>(((List<?>) value).size());
-			for (Object listValue : (List<?>) value) {
-				convertedList.add(this.convertLongStringIfNecessary(listValue, charset));
-			}
-			value = convertedList;
+
+		if (valueArg instanceof List<?> values) {
+			List<Object> convertedList = new ArrayList<>(values.size());
+			values.forEach(value -> convertedList.add(this.convertLongStringIfNecessary(value, charset)));
+			return convertedList;
 		}
-		else if (value instanceof Map<?, ?>) {
-			@SuppressWarnings("unchecked")
-			Map<String, Object> originalMap = (Map<String, Object>) value;
+
+		if (valueArg instanceof Map<?, ?> originalMap) {
 			Map<String, Object> convertedMap = new HashMap<>();
-			for (Map.Entry<String, Object> entry : originalMap.entrySet()) {
-				convertedMap.put(entry.getKey(), this.convertLongStringIfNecessary(entry.getValue(), charset));
-			}
-			value = convertedMap;
+			originalMap.forEach(
+				(key, value) -> convertedMap.put((String) key, this.convertLongStringIfNecessary(value, charset)));
+			return convertedMap;
 		}
-		return value;
+
+		return valueArg;
 	}
 
 }