Fix #637: merge namespace information properly

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -16,6 +16,8 @@ Project: jackson-dataformat-xml
   `XmlMapper.createParser(XMLStreamReader)` overloads
 #634: Support use of xsi:type for polymorphic deserialization
   (FromXmlParser.Feature.AUTO_DETECT_XSI_TYPE)
+#637: `JacksonXmlAnnotationIntrospector.findNamespace()` should
+  properly merge namespace information
 * Upgrade Woodstox to 6.6.0 (latest at the time)
 
 2.16.1 (24-Dec-2023)

src/main/java/com/fasterxml/jackson/dataformat/xml/JacksonXmlAnnotationIntrospector.java

@@ -117,16 +117,27 @@ public PropertyName findRootName(AnnotatedClass ac)
     @Override
     public String findNamespace(MapperConfig<?> config, Annotated ann)
     {
-        JacksonXmlProperty prop = _findAnnotation(ann, JacksonXmlProperty.class);
-        if (prop != null) {
-            return prop.namespace();
+        String ns1 = null;
+        JacksonXmlProperty xmlProp = _findAnnotation(ann, JacksonXmlProperty.class);
+        if (xmlProp != null) {
+            ns1 = xmlProp.namespace();
         }
         // 14-Nov-2020, tatu: 2.12 adds namespace for this too
         JsonProperty jprop = _findAnnotation(ann, JsonProperty.class);
+        String ns2 = null;
         if (jprop != null) {
-            return jprop.namespace();
+            ns2 = jprop.namespace();
         }
-        return null;
+        if (ns1 == null) {
+            return ns2;
+        }
+        if (ns2 == null) {
+            return ns2;
+        }
+        if (ns1.isEmpty()) {
+            return ns2;
+        }
+        return ns1;
     }
 
     /**

src/test/java/com/fasterxml/jackson/dataformat/xml/ser/SerializationNameMergingTest.java

@@ -0,0 +1,29 @@
+package com.fasterxml.jackson.dataformat.xml.ser;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.dataformat.xml.XmlMapper;
+import com.fasterxml.jackson.dataformat.xml.XmlTestBase;
+import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
+
+// [dataformat-xml#637]
+public class SerializationNameMergingTest extends XmlTestBase
+{
+    // [dataformat-xml#637]
+    static class NamesBean {
+        // XML annotations have precedence over default/standard/json ones
+        // but local name, namespace should be merged
+        @JsonProperty(value="value", namespace="uri:ns1")
+        @JacksonXmlProperty(isAttribute=true)
+        public int valueDefault = 42;
+    }
+
+    private final XmlMapper MAPPER = newMapper();
+
+
+    // [dataformat-xml#637]
+    public void testNamespaceMerging637() throws Exception
+    {
+        assertEquals(a2q("<NamesBean xmlns:wstxns1='uri:ns1' wstxns1:value='42'/>"),
+                MAPPER.writeValueAsString(new NamesBean()));
+    }
+}