Add unit tests for DomTrip wrapper classes and fix Properties.put contract

- Add 8 test classes (147 tests) covering all DomTrip wrapper classes:
  DomTripBuild, DomTripDependency, DomTripDependencyManagement,
  DomTripExtension, DomTripModel, DomTripParent, DomTripProperties,
  DomTripScm
- Fix DomTripProperties.put() to return the previous value per the
  Hashtable.put contract instead of always returning null

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: gnodet

maven-release-manager/src/main/java/org/apache/maven/shared/release/transform/domtrip/DomTripProperties.java

@@ -52,14 +52,15 @@ public DomTripProperties(Element properties, Editor editor) {
     @Override
     public synchronized Object put(Object key, Object value) {
         Element property = properties.childElement((String) key).orElse(null);
+        String oldValue;
         if (property != null) {
+            oldValue = property.textContentTrimmed();
             DomTripUtils.rewriteValue(editor, property, (String) value);
         } else {
+            oldValue = null;
             editor.addElement(properties, (String) key, (String) value);
         }
-
-        // todo follow specs of Hashtable.put
-        return null;
+        return oldValue;
     }
 
     @Override

maven-release-manager/src/test/java/org/apache/maven/shared/release/transform/domtrip/DomTripBuildTest.java

@@ -0,0 +1,310 @@
+/*
+ * 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.shared.release.transform.domtrip;
+
+import eu.maveniverse.domtrip.Document;
+import eu.maveniverse.domtrip.Editor;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class DomTripBuildTest {
+
+    private DomTripBuild createBuild(String xml) {
+        Document document = Document.of(xml);
+        Editor editor = new Editor(document);
+        return new DomTripBuild(document.root(), editor);
+    }
+
+    @Test
+    void testGetExtensionsEmpty() {
+        assertNotNull(createBuild("<build></build>").getExtensions());
+        assertEquals(0, createBuild("<build></build>").getExtensions().size());
+    }
+
+    @Test
+    void testGetExtensionsEmptyContainer() {
+        assertEquals(
+                0, createBuild("<build><extensions/></build>").getExtensions().size());
+    }
+
+    @Test
+    void testGetExtensionsOne() {
+        assertEquals(
+                1,
+                createBuild("<build><extensions><extension/></extensions></build>")
+                        .getExtensions()
+                        .size());
+    }
+
+    @Test
+    void testGetPluginManagementMissing() {
+        assertNull(createBuild("<build></build>").getPluginManagement());
+    }
+
+    @Test
+    void testGetPluginManagementPresent() {
+        assertNotNull(createBuild("<build><pluginManagement/></build>").getPluginManagement());
+    }
+
+    @Test
+    void testGetPluginsEmpty() {
+        assertNotNull(createBuild("<build></build>").getPlugins());
+        assertEquals(0, createBuild("<build></build>").getPlugins().size());
+    }
+
+    @Test
+    void testGetPluginsEmptyContainer() {
+        assertEquals(0, createBuild("<build><plugins/></build>").getPlugins().size());
+    }
+
+    @Test
+    void testGetPluginsOne() {
+        assertEquals(
+                1,
+                createBuild("<build><plugins><plugin/></plugins></build>")
+                        .getPlugins()
+                        .size());
+    }
+
+    @Test
+    void testFlushPluginMap() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .flushPluginMap());
+    }
+
+    @Test
+    void testAddExtension() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .addExtension(null));
+    }
+
+    @Test
+    void testGetOutputDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getOutputDirectory());
+    }
+
+    @Test
+    void testGetScriptSourceDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getScriptSourceDirectory());
+    }
+
+    @Test
+    void testGetSourceDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getSourceDirectory());
+    }
+
+    @Test
+    void testGetTestOutputDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getTestOutputDirectory());
+    }
+
+    @Test
+    void testGetTestSourceDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getTestSourceDirectory());
+    }
+
+    @Test
+    void testRemoveExtension() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .removeExtension(null));
+    }
+
+    @Test
+    void testSetExtensions() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setExtensions(null));
+    }
+
+    @Test
+    void testSetOutputDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setOutputDirectory(null));
+    }
+
+    @Test
+    void testSetScriptSourceDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setScriptSourceDirectory(null));
+    }
+
+    @Test
+    void testSetSourceDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setSourceDirectory(null));
+    }
+
+    @Test
+    void testSetTestOutputDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setTestOutputDirectory(null));
+    }
+
+    @Test
+    void testSetTestSourceDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setTestSourceDirectory(null));
+    }
+
+    @Test
+    void testAddFilter() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .addFilter(null));
+    }
+
+    @Test
+    void testAddResource() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .addResource(null));
+    }
+
+    @Test
+    void testAddTestResource() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .addTestResource(null));
+    }
+
+    @Test
+    void testGetDefaultGoal() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getDefaultGoal());
+    }
+
+    @Test
+    void testGetDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getDirectory());
+    }
+
+    @Test
+    void testGetFilters() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getFilters());
+    }
+
+    @Test
+    void testGetFinalName() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getFinalName());
+    }
+
+    @Test
+    void testGetResources() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getResources());
+    }
+
+    @Test
+    void testGetTestResources() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getTestResources());
+    }
+
+    @Test
+    void testRemoveFilter() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .removeFilter(null));
+    }
+
+    @Test
+    void testRemoveResource() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .removeResource(null));
+    }
+
+    @Test
+    void testRemoveTestResource() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .removeTestResource(null));
+    }
+
+    @Test
+    void testSetDefaultGoal() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setDefaultGoal(null));
+    }
+
+    @Test
+    void testSetDirectory() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setDirectory(null));
+    }
+
+    @Test
+    void testSetFilters() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setFilters(null));
+    }
+
+    @Test
+    void testSetFinalName() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setFinalName(null));
+    }
+
+    @Test
+    void testSetResources() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setResources(null));
+    }
+
+    @Test
+    void testSetTestResources() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setTestResources(null));
+    }
+
+    @Test
+    void testSetPluginManagement() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setPluginManagement(null));
+    }
+
+    @Test
+    void testAddPlugin() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .addPlugin(null));
+    }
+
+    @Test
+    void testRemovePlugin() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .removePlugin(null));
+    }
+
+    @Test
+    void testSetPlugins() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .setPlugins(null));
+    }
+
+    @Test
+    void testGetPluginsAsMap() {
+        assertThrows(UnsupportedOperationException.class, () -> createBuild("<build/>")
+                .getPluginsAsMap());
+    }
+}