(maven) branch maven-4.0.x updated: Add XmlService classloader fallback for ServiceLoader discovery (#12254)

[gnodet]

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gnodet pushed a commit to branch maven-4.0.x
in repository https://gitbox.apache.org/repos/asf/maven.git


The following commit(s) were added to refs/heads/maven-4.0.x by this push:
     new aa3783fcff Add XmlService classloader fallback for ServiceLoader 
discovery (#12254)
aa3783fcff is described below

commit aa3783fcff1947ac3bc94f0af25186126c794ca0
Author: Guillaume Nodet <gno...@gmail.com>
AuthorDate: Sun Jun 14 00:20:03 2026 +0200

    Add XmlService classloader fallback for ServiceLoader discovery (#12254)
    
    * Add XmlService classloader fallback for ServiceLoader discovery
    
    When the thread context classloader cannot see the XmlService
    provider (e.g. in plugin classloaders), fall back to loading
    via XmlService's own classloader. This prevents
    IllegalStateException("No XmlService implementation found")
    in environments where the TCCL is isolated.
    
    
    
    * Use import instead of FQCN for Optional
    
    
    
    ---------
    
    Co-authored-by: Arturo Bernal <aber...@apache.org>
    Co-authored-by: Claude Opus 4.6 <nore...@anthropic.com>
---
 .../java/org/apache/maven/api/xml/XmlService.java  | 10 ++++-
 .../maven/internal/xml/XmlServiceLoadingTest.java  | 44 ++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git 
a/api/maven-api-xml/src/main/java/org/apache/maven/api/xml/XmlService.java 
b/api/maven-api-xml/src/main/java/org/apache/maven/api/xml/XmlService.java
index e6735e255f..ea4b1593d4 100644
--- a/api/maven-api-xml/src/main/java/org/apache/maven/api/xml/XmlService.java
+++ b/api/maven-api-xml/src/main/java/org/apache/maven/api/xml/XmlService.java
@@ -25,6 +25,7 @@
 import java.io.InputStream;
 import java.io.Reader;
 import java.io.Writer;
+import java.util.Optional;
 import java.util.ServiceLoader;
 
 import org.apache.maven.api.annotations.Nonnull;
@@ -239,8 +240,15 @@ private static XmlService getService() {
 
     /** Holder class for lazy initialization of the default instance */
     private static final class Holder {
-        static final XmlService INSTANCE = ServiceLoader.load(XmlService.class)
+        static final XmlService INSTANCE = 
ServiceLoader.load(XmlService.class, XmlService.class.getClassLoader())
                 .findFirst()
+                .or(() -> {
+                    ClassLoader contextClassLoader = 
Thread.currentThread().getContextClassLoader();
+                    return contextClassLoader != null
+                            ? ServiceLoader.load(XmlService.class, 
contextClassLoader)
+                                    .findFirst()
+                            : Optional.empty();
+                })
                 .orElseThrow(() -> new IllegalStateException("No XmlService 
implementation found"));
 
         private Holder() {}
diff --git 
a/impl/maven-xml/src/test/java/org/apache/maven/internal/xml/XmlServiceLoadingTest.java
 
b/impl/maven-xml/src/test/java/org/apache/maven/internal/xml/XmlServiceLoadingTest.java
new file mode 100644
index 0000000000..f511074263
--- /dev/null
+++ 
b/impl/maven-xml/src/test/java/org/apache/maven/internal/xml/XmlServiceLoadingTest.java
@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.internal.xml;
+
+import java.io.StringReader;
+import java.net.URL;
+import java.net.URLClassLoader;
+
+import org.apache.maven.api.xml.XmlNode;
+import org.apache.maven.api.xml.XmlService;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class XmlServiceLoadingTest {
+
+    @Test
+    void testServiceLoaderFallbackWhenContextClassLoaderCannotSeeProvider() 
throws Exception {
+        ClassLoader previous = Thread.currentThread().getContextClassLoader();
+        try (URLClassLoader contextClassLoader = new URLClassLoader(new 
URL[0], null)) {
+            Thread.currentThread().setContextClassLoader(contextClassLoader);
+            XmlNode node = XmlService.read(new 
StringReader("<configuration/>"));
+            assertEquals("configuration", node.name());
+        } finally {
+            Thread.currentThread().setContextClassLoader(previous);
+        }
+    }
+}