fix: don't use custom BeanPropertyWriter for xml module (#7170)

Our BeanIntrospectionPropertyWriter is fundamentally incompatible with the XmlBeanPropertyWriter. This patch skips use of our writer if the xml writer is present, to preserve the proper xml serialization behavior.

The biggest disadvantage to this approach is that it only works if reflection is available. There also isn't the perf improvement of BeanIntrospectionPropertyWriter.

An alternative here would be to add support for the XML features to the BeanIntrospectionModule. I tried a limited version of this (only the features directly supported by the XmlBeanPropertyWriter), and it works, but only with reflection available. So the native-image issue remains unresolved even with the limited xml support.

Full XML support without reflection would basically need a reimpl of big parts of jackson-dataformat-xml, which is certainly out of scope for micronaut-jackson-databind, though it could be a future feature of micronaut-xml.

Fixes #5907

jackson-databind/build.gradle

@@ -31,6 +31,7 @@ dependencies {
     testImplementation project(":inject-java")
     testImplementation project(":inject-java-test")
     testImplementation project(":inject-groovy")
+    testImplementation "com.fasterxml.jackson.dataformat:jackson-dataformat-xml"
     if (!JavaVersion.current().isJava9Compatible()) {
         testImplementation files(org.gradle.internal.jvm.Jvm.current().toolsJar)
     }

jackson-databind/src/main/java/io/micronaut/jackson/modules/BeanIntrospectionModule.java

@@ -343,7 +343,10 @@ public JsonSerializer<?> build() {
                         final Optional<BeanProperty<Object, Object>> property = Optional.ofNullable(named.get(existing.getName()));
                         // ignore properties that are @JsonIgnore, so that we don't replace other properties of the
                         // same name
-                        if (property.isPresent() && !property.get().isAnnotationPresent(JsonIgnore.class)) {
+                        if (property.isPresent() &&
+                                !property.get().isAnnotationPresent(JsonIgnore.class) &&
+                                // we can't support XmlBeanPropertyWriter easily https://github.com/micronaut-projects/micronaut-core/issues/5907
+                                !existing.getClass().getName().equals("com.fasterxml.jackson.dataformat.xml.ser.XmlBeanPropertyWriter")) { // NOSONAR
                             final BeanProperty<Object, Object> beanProperty = property.get();
                             newProperties.set(i, new BeanIntrospectionPropertyWriter(
                                         existing,

jackson-databind/src/test/groovy/io/micronaut/jackson/modules/BeanIntrospectionModuleSpec.groovy

@@ -21,6 +21,8 @@ import com.fasterxml.jackson.databind.SerializerProvider
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize
 import com.fasterxml.jackson.databind.annotation.JsonNaming
 import com.fasterxml.jackson.databind.annotation.JsonSerialize
+import com.fasterxml.jackson.dataformat.xml.XmlMapper
+import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper
 import groovy.transform.EqualsAndHashCode
 import groovy.transform.PackageScope
 import io.micronaut.context.ApplicationContext
@@ -965,6 +967,31 @@ class BeanIntrospectionModuleSpec extends Specification {
         }
     }
 
+    @Issue('https://github.com/micronaut-projects/micronaut-core/issues/5907')
+    void "xml modifier"() {
+        given:
+        ApplicationContext ctx = ApplicationContext.run()
+        XmlMapper objectMapper = new XmlMapper()
+        objectMapper.registerModule(ctx.getBean(BeanIntrospectionModule))
+
+        expect:
+        objectMapper.writeValueAsString(new UsesXmlElementWrapper()) ==
+                '<UsesXmlElementWrapper><nestedItems><strings>foo</strings><strings>bar</strings></nestedItems></UsesXmlElementWrapper>'
+
+        cleanup:
+        ctx.close()
+    }
+
+    @Introspected
+    static class UsesXmlElementWrapper {
+        private List<String> strings = ["foo", "bar"];
+
+        @JacksonXmlElementWrapper(/*useWrapping = false, */localName = "nestedItems")
+        public List<String> getStrings() {
+            return strings
+        }
+    }
+
     @Unroll("JsonProperty annotation is supported with ignoreReflectiveProperties: #ignoreReflectiveProperties")
     void "JsonProperty support"(boolean ignoreReflectiveProperties) {
         given: