Support configureForJackson2() with XmlMapper

src/main/java/tools/jackson/dataformat/xml/XmlFactory.java

@@ -167,6 +167,18 @@ public static XmlFactoryBuilder builder() {
         return new XmlFactoryBuilder();
     }
 
+    /**
+     * The builder returned uses default settings more closely
+     * matching the default configs used in Jackson 2.x versions.
+     * <p>
+     *     This method is still a work in progress and may not yet fully replicate the
+     *     default settings of Jackson 2.x.
+     * </p>
+     */
+    public static XmlFactoryBuilder builderWithJackson2Defaults() {
+        return builder().configureForJackson2();
+    }
+
     /**
      * Note: compared to base implementation by {@link TokenStreamFactory},
      * here the copy will actually share underlying XML input and

src/main/java/tools/jackson/dataformat/xml/XmlFactoryBuilder.java

@@ -222,6 +222,23 @@ public XmlFactoryBuilder configure(XmlWriteFeature f, boolean state) {
         return state ? enable(f) : disable(f);
     }
 
+    /**
+     * The builder returned uses default settings more closely
+     * matching the default configs used in Jackson 2.x versions.
+     * <p>
+     *     This method is still a work in progress and may not yet fully replicate the
+     *     default settings of Jackson 2.x.
+     * </p>
+     */
+    @Override
+    public XmlFactoryBuilder configureForJackson2() {
+        return super.configureForJackson2()
+                .disable(XmlWriteFeature.WRITE_NULLS_AS_XSI_NIL)
+                .disable(XmlWriteFeature.UNWRAP_ROOT_OBJECT_NODE)
+                .disable(XmlWriteFeature.AUTO_DETECT_XSI_TYPE)
+                .disable(XmlWriteFeature.WRITE_XML_SCHEMA_CONFORMING_FLOATS);
+    }
+
     // // // Other config
 
     public XmlFactoryBuilder nameForTextElement(String name) {

src/main/java/tools/jackson/dataformat/xml/XmlMapper.java

@@ -235,6 +235,23 @@ public Builder configure(XmlWriteFeature feature, boolean state)
             return this;
         }
 
+        /**
+         * The builder returned uses default settings more closely
+         * matching the default configs used in Jackson 2.x versions.
+         * <p>
+         *     This method is still a work in progress and may not yet fully replicate the
+         *     default settings of Jackson 2.x.
+         * </p>
+         */
+        @Override
+        public Builder configureForJackson2() {
+            return super.configureForJackson2()
+                    .disable(XmlWriteFeature.WRITE_NULLS_AS_XSI_NIL)
+                    .disable(XmlWriteFeature.UNWRAP_ROOT_OBJECT_NODE)
+                    .disable(XmlWriteFeature.AUTO_DETECT_XSI_TYPE)
+                    .disable(XmlWriteFeature.WRITE_XML_SCHEMA_CONFORMING_FLOATS);
+        }
+
         /*
         /******************************************************************
         /* XML specific additional config
@@ -340,6 +357,19 @@ public static XmlMapper.Builder builder(XmlFactory streamFactory) {
         return new XmlMapper.Builder(streamFactory);
     }
 
+    /**
+     * The builder returned uses default settings more closely
+     * matching the default configs used in Jackson 2.x versions.
+     * <p>
+     *     This method is still a work in progress and may not yet fully replicate the
+     *     default settings of Jackson 2.x.
+     * </p>
+     */
+    public static XmlMapper.Builder builderWithJackson2Defaults() {
+        return builder(XmlFactory.builderWithJackson2Defaults().build())
+                .configureForJackson2();
+    }
+
     @SuppressWarnings("unchecked")
     @Override
     public XmlMapper.Builder rebuild() {

src/test/java/tools/jackson/dataformat/xml/XmlMapperTest.java

@@ -0,0 +1,40 @@
+package tools.jackson.dataformat.xml;
+
+import org.junit.jupiter.api.Test;
+import tools.jackson.core.StreamReadFeature;
+import tools.jackson.dataformat.xml.ser.ToXmlGenerator;
+
+import javax.xml.stream.XMLOutputFactory;
+import javax.xml.stream.XMLStreamWriter;
+
+import java.io.ByteArrayOutputStream;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+public class XmlMapperTest extends XmlTestUtil
+{
+
+    @Test
+    public void testBuilderWithJackson2Defaults() throws Exception
+    {
+        XmlMapper mapper = XmlMapper.builderWithJackson2Defaults().build();
+        assertFalse(mapper.isEnabled(StreamReadFeature.USE_FAST_DOUBLE_PARSER));
+        assertFalse(mapper.isEnabled(StreamReadFeature.USE_FAST_BIG_NUMBER_PARSER));
+
+        XMLOutputFactory outputFactory = mapper.tokenStreamFactory().getXMLOutputFactory();
+        try (
+                ByteArrayOutputStream bos = new ByteArrayOutputStream();
+                ToXmlGenerator gen =
+                     mapper.createGenerator(
+                             outputFactory.createXMLStreamWriter(bos))
+        ) {
+            assertFalse(gen.isEnabled(XmlWriteFeature.WRITE_NULLS_AS_XSI_NIL));
+            assertFalse(gen.isEnabled(XmlWriteFeature.UNWRAP_ROOT_OBJECT_NODE));
+            assertFalse(gen.isEnabled(XmlWriteFeature.AUTO_DETECT_XSI_TYPE));
+            assertFalse(gen.isEnabled(XmlWriteFeature.WRITE_XML_SCHEMA_CONFORMING_FLOATS));
+            // need to write something to the generator to avoid exception
+            final Point p = new Point(1, 2);
+            mapper.writeValue(gen, p);
+        }
+    }
+}