Fix support of lambda objects for Java 21 and above. Closes #349.

xstream-distribution/src/content/changes.html

@@ -115,6 +115,7 @@ <h2>Minor changes</h2>
 		<li>GHPR:#331, GHI:#326: Fix handling of empty java.util.concurrent.atomic.AtomicReference (by Alex Blekhman of Atlassian).</li>
 		<li>GHPR:#334: Fix remaining buffer size calculation in QuickWriter (by Higuchi Yuta).</li>
 		<li>GHI:#342: Optimize internal handling of children in DomReader avoiding O(n²) access times for siblings (by Shiang-Yun Yang).</li>
+		<li>GHPR:#349: Fix support of lambda objects for Java 21 and above (Tobias Gierke).</li>
 		<li>GHI:#359: Add KEYS file with public keys to verify signed artifacts.</li>
 		<li>Detect input manipulation in c.t.x.io.binary.BinaryStreamReader.</li>
 	</ul>

xstream/src/java/com/thoughtworks/xstream/core/util/Types.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015 XStream Committers.
+ * Copyright (C) 2015, 2024 XStream Committers.
  * All rights reserved.
  *
  * Created on 17. January 2015 by Joerg Schaible
@@ -16,10 +16,13 @@
  * @since 1.4.8
  */
 public class Types {
-    private static final Pattern lambdaPattern = Pattern.compile(".*\\$\\$Lambda\\$[0-9]+/.*");
+    private static final Pattern lambdaPattern = Pattern.compile(".*\\$\\$Lambda(?:\\$[0-9]+|)/.*");
 
     public static final boolean isLambdaType(final Class<?> type) {
-        return type != null && type.isSynthetic() && lambdaPattern.matcher(type.getSimpleName()).matches();
+        if (type != null && type.isSynthetic()) {
+            final String typeName = type.getSimpleName();
+            return lambdaPattern.matcher(typeName).matches();
+        }
+        return false;
     }
-
 }