fix(serialization): avoid wrapping @JsonAnyGetter properties

The previous check used writer.getName().equals("additionalProperties"),
which failed for variations like getAdditionalProperties or when
@JsonProperty was used.

Changes:
- Skip wrapping the any-getter property in BeanSerializerModifier
- Add isAnyGetterWriter(...) to match the correct property by member

Resolved test failures:

io.fabric8.kubernetes.client.utils.SerializationAdditionalPropertiesTest
- marshalWithAdditionalPropertiesOverridingFields
- cloneShouldPreserveAdditionalProperties

Author: r1c4r60

kubernetes-model-generator/kubernetes-model-common/src/main/java/io/fabric8/kubernetes/model/jackson/UnmatchedFieldTypeModule.java

@@ -26,6 +26,7 @@
 import com.fasterxml.jackson.databind.ser.BeanSerializerBuilder;
 import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;
 
+import java.lang.reflect.Member;
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -64,23 +65,40 @@ public BeanDeserializerBuilder updateBuilder(DeserializationConfig config, BeanD
       }
     });
     setSerializerModifier(new BeanSerializerModifier() {
+      /**
+       * Customizes property writers used during serialization.
+       *
+       * This method wraps standard property writers in a delegate that can suppress serialization
+       * of fields that may be overridden by values in the map returned by {@code @JsonAnyGetter}.
+       *
+       * The property corresponding to the {@code @JsonAnyGetter} method itself is left unmodified
+       * to avoid interfering with Jackson’s internal handling via {@link com.fasterxml.jackson.databind.ser.AnyGetterWriter}.
+       *
+       * This mechanism ensures that if a field is both explicitly declared and also present in the
+       * any-getter map, only the value from the any-getter is serialized, avoiding duplication or conflicts.
+       */
       @Override
       public BeanSerializerBuilder updateBuilder(SerializationConfig config, BeanDescription beanDesc,
           BeanSerializerBuilder builder) {
         AnnotatedMember anyGetter = beanDesc.findAnyGetter();
+        Member anyGetterMember = (anyGetter != null) ? anyGetter.getMember() : null;
 
-        List<BeanPropertyWriter> originalWriters = builder.getProperties();
-
-        List<BeanPropertyWriter> newWriters = originalWriters.stream()
+        // Wrap each property writer unless it's the any-getter (handled by Jackson separately)
+        List<BeanPropertyWriter> customWriters = builder.getProperties().stream()
             .map(writer -> {
-              if ("additionalProperties".equals(writer.getName())) {
+              if (isAnyGetterWriter(writer, anyGetterMember)) {
+                // Skipping wrapping for any-getter to avoid interfering with Jackson's internal handling
                 return writer;
               }
-              return new BeanPropertyWriterDelegate(writer, anyGetter, UnmatchedFieldTypeModule.this::isLogWarnings);
+              // Wrap normal field writers with delegate to handle overrides and logging
+              return new BeanPropertyWriterDelegate(
+                  writer,
+                  anyGetter,
+                  UnmatchedFieldTypeModule.this::isLogWarnings);
             })
             .collect(Collectors.toList());
 
-        builder.setProperties(newWriters);
+        builder.setProperties(customWriters);
         return builder;
       }
     });
@@ -128,4 +146,22 @@ public static void removeInTemplate() {
     IN_TEMPLATE.remove();
   }
 
+  /**
+   * Checks whether the given {@link BeanPropertyWriter} corresponds to the method annotated with {@code @JsonAnyGetter}.
+   *
+   * This is used to identify and exclude the any-getter property from custom wrapping,
+   * since Jackson handles it separately via {@link com.fasterxml.jackson.databind.ser.AnyGetterWriter}.
+   *
+   * @param writer the property writer to examine
+   * @param anyGetterMember the reflective member (method or field) marked with {@code @JsonAnyGetter}, if available
+   * @return {@code true} if the writer represents the any-getter property; {@code false} otherwise
+   */
+  private boolean isAnyGetterWriter(BeanPropertyWriter writer, Member anyGetterMember) {
+    if (writer == null || anyGetterMember == null) {
+      return false;
+    }
+    AnnotatedMember annotated = writer.getMember();
+    Member member = (annotated != null) ? annotated.getMember() : null;
+    return member != null && member.equals(anyGetterMember);
+  }
 }