fix: remove change listener after removing child configuration object (#8215) (#8226)

Co-authored-by: Sascha Ißbrücker <sissbruecker@vaadin.com>

Author: vaadin-bot

vaadin-map-flow-parent/vaadin-map-flow/src/main/java/com/vaadin/flow/component/map/configuration/AbstractConfigurationObject.java

@@ -93,6 +93,7 @@ public abstract class AbstractConfigurationObject implements Serializable {
 
     protected final PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(
             this);
+    private final SerializablePropertyChangeListener childChangeListener = this::notifyChange;
 
     public AbstractConfigurationObject() {
         this.id = UUID.randomUUID().toString();
@@ -165,7 +166,7 @@ protected void addChild(AbstractConfigurationObject configurationObject) {
         Objects.requireNonNull(configurationObject,
                 "Child configuration object must not be null");
         children.add(configurationObject);
-        configurationObject.addPropertyChangeListener(this::notifyChange);
+        configurationObject.addPropertyChangeListener(childChangeListener);
         markAsDirty();
         // When adding a sub-hierarchy, we need to make sure that the client
         // receives the whole hierarchy. Otherwise objects that have been synced
@@ -198,7 +199,7 @@ protected void removeChild(
         if (configurationObject == null)
             return;
         children.remove(configurationObject);
-        configurationObject.removePropertyChangeListener(this::notifyChange);
+        configurationObject.removePropertyChangeListener(childChangeListener);
         markAsDirty();
     }
 

vaadin-map-flow-parent/vaadin-map-flow/src/main/java/com/vaadin/flow/component/map/configuration/SerializablePropertyChangeListener.java

@@ -0,0 +1,19 @@
+/**
+ * Copyright 2000-2025 Vaadin Ltd.
+ *
+ * This program is available under Vaadin Commercial License and Service Terms.
+ *
+ * See {@literal <https://vaadin.com/commercial-license-and-service-terms>} for the full
+ * license.
+ */
+package com.vaadin.flow.component.map.configuration;
+
+import java.beans.PropertyChangeListener;
+import java.io.Serializable;
+
+/**
+ * A {@link PropertyChangeListener} that is also {@link Serializable}.
+ */
+public interface SerializablePropertyChangeListener
+        extends PropertyChangeListener, Serializable {
+}

vaadin-map-flow-parent/vaadin-map-flow/src/test/java/com/vaadin/flow/component/map/configuration/AbstractConfigurationObjectTest.java

@@ -123,6 +123,30 @@ public void setNestedObject_marksNestedHierarchyAsDirty() {
         Mockito.verify(changeCollectorMock).accept(testConfiguration);
     }
 
+    @Test
+    public void setNestedObject_addsAndRemovesChangeListener() {
+        TestConfiguration nestedObject = new TestConfiguration();
+        Assert.assertFalse(nestedObject.hasListeners());
+
+        testConfiguration.setNestedConfiguration(nestedObject);
+        Assert.assertTrue(nestedObject.hasListeners());
+
+        testConfiguration.addPropertyChangeListener(changeListenerMock);
+
+        nestedObject.setFoo("test");
+        Mockito.verify(changeListenerMock, Mockito.times(1))
+                .propertyChange(Mockito.any());
+
+        testConfiguration.setNestedConfiguration(null);
+        Assert.assertFalse(nestedObject.hasListeners());
+        Mockito.verify(changeListenerMock, Mockito.times(2))
+                .propertyChange(Mockito.any());
+
+        nestedObject.setFoo("anotherTest");
+        Mockito.verify(changeListenerMock, Mockito.times(2))
+                .propertyChange(Mockito.any());
+    }
+
     @Test
     public void removeChangeListener_doesNotNotifyChanges() {
         testConfiguration.addPropertyChangeListener(changeListenerMock);
@@ -289,13 +313,17 @@ public void setNestedConfiguration(
                 TestConfiguration nestedConfiguration) {
             removeChild(this.nestedConfiguration);
             this.nestedConfiguration = nestedConfiguration;
-            addChild(nestedConfiguration);
+            addNullableChild(nestedConfiguration);
         }
 
         // Expose method for testing
         @Override
         protected void deepMarkAsDirty() {
             super.deepMarkAsDirty();
         }
+
+        protected boolean hasListeners() {
+            return propertyChangeSupport.hasListeners("property");
+        }
     }
 }