Support XmlSeeAlso in Jaxb2XmlDecoder

This commit adds support for the @XmlSeeAlso annotation in the
Jaxb2XmlDecoder. This includes

- Finding the set of possible qualified names given a class name, rather
  than a single name.
- Splitting the XMLEvent stream when coming across one of the names in
  this set.

Closes gh-30167

spring-web/src/main/java/org/springframework/http/codec/xml/Jaxb2Helper.java

@@ -0,0 +1,192 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http.codec.xml;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.BiConsumer;
+
+import javax.xml.XMLConstants;
+import javax.xml.namespace.QName;
+import javax.xml.stream.events.XMLEvent;
+
+import jakarta.xml.bind.annotation.XmlRootElement;
+import jakarta.xml.bind.annotation.XmlSchema;
+import jakarta.xml.bind.annotation.XmlSeeAlso;
+import jakarta.xml.bind.annotation.XmlType;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.SynchronousSink;
+
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
+/**
+ * Helper class for JAXB2.
+ *
+ * @author Arjen Poutsma
+ * @since 6.1
+ */
+abstract class Jaxb2Helper {
+
+	/**
+	 * The default value for JAXB annotations.
+	 * @see XmlRootElement#name()
+	 * @see XmlRootElement#namespace()
+	 * @see XmlType#name()
+	 * @see XmlType#namespace()
+	 */
+	private static final String JAXB_DEFAULT_ANNOTATION_VALUE = "##default";
+
+
+	/**
+	 * Returns the set of qualified names for the given class, according to the
+	 * mapping rules in the JAXB specification.
+	 */
+	public static Set<QName> toQNames(Class<?> clazz) {
+		Set<QName> result = new HashSet<>(1);
+		findQNames(clazz, result, new HashSet<>());
+		return result;
+	}
+
+	private static void findQNames(Class<?> clazz, Set<QName> qNames, Set<Class<?>> completedClasses) {
+		// safety against circular XmlSeeAlso references
+		if (completedClasses.contains(clazz)) {
+			return;
+		}
+		if (clazz.isAnnotationPresent(XmlRootElement.class)) {
+			XmlRootElement annotation = clazz.getAnnotation(XmlRootElement.class);
+			qNames.add(new QName(namespace(annotation.namespace(), clazz),
+					localPart(annotation.name(), clazz)));
+		}
+		else if (clazz.isAnnotationPresent(XmlType.class)) {
+			XmlType annotation = clazz.getAnnotation(XmlType.class);
+			qNames.add(new QName(namespace(annotation.namespace(), clazz),
+					localPart(annotation.name(), clazz)));
+		}
+		else {
+			throw new IllegalArgumentException("Output class [" + clazz.getName() +
+					"] is neither annotated with @XmlRootElement nor @XmlType");
+		}
+		completedClasses.add(clazz);
+		if (clazz.isAnnotationPresent(XmlSeeAlso.class)) {
+			XmlSeeAlso annotation = clazz.getAnnotation(XmlSeeAlso.class);
+			for (Class<?> seeAlso : annotation.value()) {
+				findQNames(seeAlso, qNames, completedClasses);
+			}
+		}
+	}
+
+	private static String localPart(String value, Class<?> outputClass) {
+		if (JAXB_DEFAULT_ANNOTATION_VALUE.equals(value)) {
+			return ClassUtils.getShortNameAsProperty(outputClass);
+		}
+		else {
+			return value;
+		}
+	}
+
+	private static String namespace(String value, Class<?> outputClass) {
+		if (JAXB_DEFAULT_ANNOTATION_VALUE.equals(value)) {
+			Package outputClassPackage = outputClass.getPackage();
+			if (outputClassPackage != null && outputClassPackage.isAnnotationPresent(XmlSchema.class)) {
+				XmlSchema annotation = outputClassPackage.getAnnotation(XmlSchema.class);
+				return annotation.namespace();
+			}
+			else {
+				return XMLConstants.NULL_NS_URI;
+			}
+		}
+		else {
+			return value;
+		}
+	}
+
+	/**
+	 * Split a flux of {@link XMLEvent XMLEvents} into a flux of XMLEvent lists, one list
+	 * for each branch of the tree that starts with one of the given qualified names.
+	 * That is, given the XMLEvents shown {@linkplain XmlEventDecoder here},
+	 * and the name "{@code child}", this method returns a flux
+	 * of two lists, each of which containing the events of a particular branch
+	 * of the tree that starts with "{@code child}".
+	 * <ol>
+	 * <li>The first list, dealing with the first branch of the tree:
+	 * <ol>
+	 * <li>{@link javax.xml.stream.events.StartElement} {@code child}</li>
+	 * <li>{@link javax.xml.stream.events.Characters} {@code foo}</li>
+	 * <li>{@link javax.xml.stream.events.EndElement} {@code child}</li>
+	 * </ol>
+	 * <li>The second list, dealing with the second branch of the tree:
+	 * <ol>
+	 * <li>{@link javax.xml.stream.events.StartElement} {@code child}</li>
+	 * <li>{@link javax.xml.stream.events.Characters} {@code bar}</li>
+	 * <li>{@link javax.xml.stream.events.EndElement} {@code child}</li>
+	 * </ol>
+	 * </li>
+	 * </ol>
+	 */
+	public static Flux<List<XMLEvent>> split(Flux<XMLEvent> xmlEventFlux, Set<QName> names) {
+		return xmlEventFlux.handle(new SplitHandler(names));
+	}
+
+
+	private static class SplitHandler implements BiConsumer<XMLEvent, SynchronousSink<List<XMLEvent>>> {
+
+		private final Set<QName> names;
+
+		@Nullable
+		private List<XMLEvent> events;
+
+		private int elementDepth = 0;
+
+		private int barrier = Integer.MAX_VALUE;
+
+		public SplitHandler(Set<QName> names) {
+			this.names = names;
+		}
+
+		@Override
+		public void accept(XMLEvent event, SynchronousSink<List<XMLEvent>> sink) {
+			if (event.isStartElement()) {
+				if (this.barrier == Integer.MAX_VALUE) {
+					QName startElementName = event.asStartElement().getName();
+					if (this.names.contains(startElementName)) {
+						this.events = new ArrayList<>();
+						this.barrier = this.elementDepth;
+					}
+				}
+				this.elementDepth++;
+			}
+			if (this.elementDepth > this.barrier) {
+				Assert.state(this.events != null, "No XMLEvent List");
+				this.events.add(event);
+			}
+			if (event.isEndElement()) {
+				this.elementDepth--;
+				if (this.elementDepth == this.barrier) {
+					this.barrier = Integer.MAX_VALUE;
+					Assert.state(this.events != null, "No XMLEvent List");
+					sink.next(this.events);
+				}
+			}
+		}
+	}
+
+
+}

spring-web/src/main/java/org/springframework/http/codec/xml/Jaxb2XmlDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,10 +21,9 @@ import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.util.function.BiConsumer;
+import java.util.Set;
 import java.util.function.Function;
 
-import javax.xml.XMLConstants;
 import javax.xml.namespace.QName;
 import javax.xml.stream.XMLEventReader;
 import javax.xml.stream.XMLInputFactory;
@@ -36,13 +35,12 @@ import jakarta.xml.bind.JAXBException;
 import jakarta.xml.bind.UnmarshalException;
 import jakarta.xml.bind.Unmarshaller;
 import jakarta.xml.bind.annotation.XmlRootElement;
-import jakarta.xml.bind.annotation.XmlSchema;
+import jakarta.xml.bind.annotation.XmlSeeAlso;
 import jakarta.xml.bind.annotation.XmlType;
 import org.reactivestreams.Publisher;
 import reactor.core.Exceptions;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
-import reactor.core.publisher.SynchronousSink;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.codec.AbstractDecoder;
@@ -54,9 +52,8 @@ import org.springframework.core.io.buffer.DataBufferLimitException;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.core.log.LogFormatUtils;
 import org.springframework.http.MediaType;
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
-import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeType;
 import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.xml.StaxUtils;
@@ -72,15 +69,6 @@ import org.springframework.util.xml.StaxUtils;
  */
 public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
 
-	/**
-	 * The default value for JAXB annotations.
-	 * @see XmlRootElement#name()
-	 * @see XmlRootElement#namespace()
-	 * @see XmlType#name()
-	 * @see XmlType#namespace()
-	 */
-	private static final String JAXB_DEFAULT_ANNOTATION_VALUE = "##default";
-
 	private static final XMLInputFactory inputFactory = StaxUtils.createDefensiveInputFactory();
 
 
@@ -162,8 +150,8 @@ public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
 				inputStream, ResolvableType.forClass(XMLEvent.class), mimeType, hints);
 
 		Class<?> outputClass = elementType.toClass();
-		QName typeName = toQName(outputClass);
+		Set<QName> typeNames = Jaxb2Helper.toQNames(outputClass);
-		Flux<List<XMLEvent>> splitEvents = split(xmlEventFlux, typeName);
+		Flux<List<XMLEvent>> splitEvents = Jaxb2Helper.split(xmlEventFlux, typeNames);
 
 		return splitEvents.map(events -> {
 			Object value = unmarshal(events, outputClass);
@@ -184,6 +172,7 @@ public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
 	}
 
 	@Override
+	@NonNull
 	public Object decode(DataBuffer dataBuffer, ResolvableType targetType,
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) throws DecodingException {
 
@@ -229,7 +218,8 @@ public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
 		try {
 			Unmarshaller unmarshaller = initUnmarshaller(outputClass);
 			XMLEventReader eventReader = StaxUtils.createXMLEventReader(events);
-			if (outputClass.isAnnotationPresent(XmlRootElement.class)) {
+			if (outputClass.isAnnotationPresent(XmlRootElement.class) ||
+				outputClass.isAnnotationPresent(XmlSeeAlso.class)) {
 				return unmarshaller.unmarshal(eventReader);
 			}
 			else {
@@ -250,113 +240,4 @@ public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
 		return this.unmarshallerProcessor.apply(unmarshaller);
 	}
 
-	/**
-	 * Returns the qualified name for the given class, according to the mapping rules
-	 * in the JAXB specification.
-	 */
-	QName toQName(Class<?> outputClass) {
-		String localPart;
-		String namespaceUri;
-
-		if (outputClass.isAnnotationPresent(XmlRootElement.class)) {
-			XmlRootElement annotation = outputClass.getAnnotation(XmlRootElement.class);
-			localPart = annotation.name();
-			namespaceUri = annotation.namespace();
-		}
-		else if (outputClass.isAnnotationPresent(XmlType.class)) {
-			XmlType annotation = outputClass.getAnnotation(XmlType.class);
-			localPart = annotation.name();
-			namespaceUri = annotation.namespace();
-		}
-		else {
-			throw new IllegalArgumentException("Output class [" + outputClass.getName() +
-					"] is neither annotated with @XmlRootElement nor @XmlType");
-		}
-
-		if (JAXB_DEFAULT_ANNOTATION_VALUE.equals(localPart)) {
-			localPart = ClassUtils.getShortNameAsProperty(outputClass);
-		}
-		if (JAXB_DEFAULT_ANNOTATION_VALUE.equals(namespaceUri)) {
-			Package outputClassPackage = outputClass.getPackage();
-			if (outputClassPackage != null && outputClassPackage.isAnnotationPresent(XmlSchema.class)) {
-				XmlSchema annotation = outputClassPackage.getAnnotation(XmlSchema.class);
-				namespaceUri = annotation.namespace();
-			}
-			else {
-				namespaceUri = XMLConstants.NULL_NS_URI;
-			}
-		}
-		return new QName(namespaceUri, localPart);
-	}
-
-	/**
-	 * Split a flux of {@link XMLEvent XMLEvents} into a flux of XMLEvent lists, one list
-	 * for each branch of the tree that starts with the given qualified name.
-	 * That is, given the XMLEvents shown {@linkplain XmlEventDecoder here},
-	 * and the {@code desiredName} "{@code child}", this method returns a flux
-	 * of two lists, each of which containing the events of a particular branch
-	 * of the tree that starts with "{@code child}".
-	 * <ol>
-	 * <li>The first list, dealing with the first branch of the tree:
-	 * <ol>
-	 * <li>{@link javax.xml.stream.events.StartElement} {@code child}</li>
-	 * <li>{@link javax.xml.stream.events.Characters} {@code foo}</li>
-	 * <li>{@link javax.xml.stream.events.EndElement} {@code child}</li>
-	 * </ol>
-	 * <li>The second list, dealing with the second branch of the tree:
-	 * <ol>
-	 * <li>{@link javax.xml.stream.events.StartElement} {@code child}</li>
-	 * <li>{@link javax.xml.stream.events.Characters} {@code bar}</li>
-	 * <li>{@link javax.xml.stream.events.EndElement} {@code child}</li>
-	 * </ol>
-	 * </li>
-	 * </ol>
-	 */
-	Flux<List<XMLEvent>> split(Flux<XMLEvent> xmlEventFlux, QName desiredName) {
-		return xmlEventFlux.handle(new SplitHandler(desiredName));
-	}
-
-
-	private static class SplitHandler implements BiConsumer<XMLEvent, SynchronousSink<List<XMLEvent>>> {
-
-		private final QName desiredName;
-
-		@Nullable
-		private List<XMLEvent> events;
-
-		private int elementDepth = 0;
-
-		private int barrier = Integer.MAX_VALUE;
-
-		public SplitHandler(QName desiredName) {
-			this.desiredName = desiredName;
-		}
-
-		@Override
-		public void accept(XMLEvent event, SynchronousSink<List<XMLEvent>> sink) {
-			if (event.isStartElement()) {
-				if (this.barrier == Integer.MAX_VALUE) {
-					QName startElementName = event.asStartElement().getName();
-					if (this.desiredName.equals(startElementName)) {
-						this.events = new ArrayList<>();
-						this.barrier = this.elementDepth;
-					}
-				}
-				this.elementDepth++;
-			}
-			if (this.elementDepth > this.barrier) {
-				Assert.state(this.events != null, "No XMLEvent List");
-				this.events.add(event);
-			}
-			if (event.isEndElement()) {
-				this.elementDepth--;
-				if (this.elementDepth == this.barrier) {
-					this.barrier = Integer.MAX_VALUE;
-					Assert.state(this.events != null, "No XMLEvent List");
-					sink.next(this.events);
-				}
-			}
-		}
-	}
-
 }

spring-web/src/test/java/org/springframework/http/codec/xml/Jaxb2HelperTests.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http.codec.xml;
+
+import javax.xml.namespace.QName;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.http.codec.xml.jaxb.XmlRootElement;
+import org.springframework.http.codec.xml.jaxb.XmlRootElementWithName;
+import org.springframework.http.codec.xml.jaxb.XmlRootElementWithNameAndNamespace;
+import org.springframework.http.codec.xml.jaxb.XmlType;
+import org.springframework.http.codec.xml.jaxb.XmlTypeSeeAlso;
+import org.springframework.http.codec.xml.jaxb.XmlTypeWithName;
+import org.springframework.http.codec.xml.jaxb.XmlTypeWithNameAndNamespace;
+import org.springframework.web.testfixture.xml.Pojo;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Arjen Poutsma
+ */
+class Jaxb2HelperTests {
+
+	@Test
+	public void toExpectedQName() {
+		assertThat(Jaxb2Helper.toQNames(Pojo.class)).containsExactly(new QName("pojo"));
+		assertThat(Jaxb2Helper.toQNames(TypePojo.class)).containsExactly(new QName("pojo"));
+
+		assertThat(Jaxb2Helper.toQNames(XmlRootElementWithNameAndNamespace.class)).containsExactly(new QName("namespace-type", "name-type"));
+		assertThat(Jaxb2Helper.toQNames(XmlRootElementWithName.class)).containsExactly(new QName("namespace-package", "name-type"));
+		assertThat(Jaxb2Helper.toQNames(XmlRootElement.class)).containsExactly(new QName("namespace-package", "xmlRootElement"));
+
+		assertThat(Jaxb2Helper.toQNames(XmlTypeWithNameAndNamespace.class)).containsExactly(new QName("namespace-type", "name-type"));
+		assertThat(Jaxb2Helper.toQNames(XmlTypeWithName.class)).containsExactly(new QName("namespace-package", "name-type"));
+		assertThat(Jaxb2Helper.toQNames(XmlType.class)).containsExactly(new QName("namespace-package", "xmlType"));
+		assertThat(Jaxb2Helper.toQNames(XmlTypeSeeAlso.class)).containsExactlyInAnyOrder(new QName("namespace-package", "xmlTypeSeeAlso"),
+				new QName("namespace-package", "name-type"), new QName("namespace-type", "name-type"));
+	}
+
+
+}

spring-web/src/test/java/org/springframework/http/codec/xml/Jaxb2XmlDecoderTests.java

@@ -20,10 +20,13 @@ import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
 
 import javax.xml.namespace.QName;
 import javax.xml.stream.events.XMLEvent;
 
+import jakarta.xml.bind.annotation.XmlSeeAlso;
 import org.junit.jupiter.api.Test;
 import reactor.core.Exceptions;
 import reactor.core.publisher.Flux;
@@ -35,13 +38,6 @@ import org.springframework.core.codec.DecodingException;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.testfixture.io.buffer.AbstractLeakCheckingTests;
 import org.springframework.http.MediaType;
-import org.springframework.http.codec.xml.jaxb.XmlRootElement;
-import org.springframework.http.codec.xml.jaxb.XmlRootElementWithName;
-import org.springframework.http.codec.xml.jaxb.XmlRootElementWithNameAndNamespace;
-import org.springframework.http.codec.xml.jaxb.XmlType;
-import org.springframework.http.codec.xml.jaxb.XmlTypeWithName;
-import org.springframework.http.codec.xml.jaxb.XmlTypeWithNameAndNamespace;
-import org.springframework.lang.Nullable;
 import org.springframework.util.MimeType;
 import org.springframework.web.testfixture.xml.Pojo;
 
@@ -96,7 +92,7 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 	@Test
 	public void splitOneBranches() {
 		Flux<XMLEvent> xmlEvents = this.xmlEventDecoder.decode(toDataBufferMono(POJO_ROOT), null, null, HINTS);
-		Flux<List<XMLEvent>> result = this.decoder.split(xmlEvents, new QName("pojo"));
+		Flux<List<XMLEvent>> result = Jaxb2Helper.split(xmlEvents, Set.of(new QName("pojo")));
 
 		StepVerifier.create(result)
 				.consumeNextWith(events -> {
@@ -117,7 +113,7 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 	@Test
 	public void splitMultipleBranches() {
 		Flux<XMLEvent> xmlEvents = this.xmlEventDecoder.decode(toDataBufferMono(POJO_CHILD), null, null, HINTS);
-		Flux<List<XMLEvent>> result = this.decoder.split(xmlEvents, new QName("pojo"));
+		Flux<List<XMLEvent>> result = Jaxb2Helper.split(xmlEvents, Set.of(new QName("pojo")));
 
 
 		StepVerifier.create(result)
@@ -208,6 +204,19 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 				.verify();
 	}
 
+	@Test
+	public void decodeXmlSeeAlso() {
+		Mono<DataBuffer> source = toDataBufferMono(POJO_CHILD);
+		Flux<Object> output = this.decoder.decode(source, ResolvableType.forClass(Parent.class), null, HINTS);
+
+		StepVerifier.create(output)
+				.expectNext(new Child("foo", "bar"))
+				.expectNext(new Child("foofoo", "barbar"))
+				.expectComplete()
+				.verify();
+
+	}
+
 	@Test
 	public void decodeError() {
 		Flux<DataBuffer> source = Flux.concat(
@@ -252,21 +261,6 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 				.verify();
 	}
 
-	@Test
-	public void toExpectedQName() {
-		assertThat(this.decoder.toQName(Pojo.class)).isEqualTo(new QName("pojo"));
-		assertThat(this.decoder.toQName(TypePojo.class)).isEqualTo(new QName("pojo"));
-
-		assertThat(this.decoder.toQName(XmlRootElementWithNameAndNamespace.class)).isEqualTo(new QName("namespace", "name"));
-		assertThat(this.decoder.toQName(XmlRootElementWithName.class)).isEqualTo(new QName("namespace", "name"));
-		assertThat(this.decoder.toQName(XmlRootElement.class)).isEqualTo(new QName("namespace", "xmlRootElement"));
-
-		assertThat(this.decoder.toQName(XmlTypeWithNameAndNamespace.class)).isEqualTo(new QName("namespace", "name"));
-		assertThat(this.decoder.toQName(XmlTypeWithName.class)).isEqualTo(new QName("namespace", "name"));
-		assertThat(this.decoder.toQName(XmlType.class)).isEqualTo(new QName("namespace", "xmlType"));
-
-	}
-
 	private Mono<DataBuffer> toDataBufferMono(String value) {
 		return Mono.defer(() -> {
 			byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
@@ -276,20 +270,17 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 		});
 	}
 
-
+	@jakarta.xml.bind.annotation.XmlType
-	@jakarta.xml.bind.annotation.XmlType(name = "pojo")
+	@XmlSeeAlso(Child.class)
-	public static class TypePojo {
+	public static abstract class Parent {
 
 		private String foo;
 
-		private String bar;
+		public Parent() {
-
-		public TypePojo() {
 		}
 
-		public TypePojo(String foo, String bar) {
+		public Parent(String foo) {
 			this.foo = foo;
-			this.bar = bar;
 		}
 
 		public String getFoo() {
@@ -299,6 +290,20 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 		public void setFoo(String foo) {
 			this.foo = foo;
 		}
+	}
+
+	@jakarta.xml.bind.annotation.XmlRootElement(name = "pojo")
+	public static class Child extends Parent {
+
+		private String bar;
+
+		public Child() {
+		}
+
+		public Child(String foo, String bar) {
+			super(foo);
+			this.bar = bar;
+		}
 
 		public String getBar() {
 			return this.bar;
@@ -309,21 +314,21 @@ public class Jaxb2XmlDecoderTests extends AbstractLeakCheckingTests {
 		}
 
 		@Override
-		public boolean equals(@Nullable Object o) {
+		public boolean equals(Object o) {
 			if (this == o) {
 				return true;
 			}
-			if (o instanceof TypePojo other) {
+			if (o instanceof Child other) {
-				return this.foo.equals(other.foo) && this.bar.equals(other.bar);
+				return getBar().equals(other.getBar()) &&
+						getFoo().equals(other.getFoo());
 			}
 			return false;
 		}
 
 		@Override
 		public int hashCode() {
-			int result = this.foo.hashCode();
+			return Objects.hash(getBar(), getFoo());
-			result = 31 * result + this.bar.hashCode();
-			return result;
 		}
 	}
+
 }

spring-web/src/test/java/org/springframework/http/codec/xml/Jaxb2XmlEncoderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -57,7 +57,7 @@ public class Jaxb2XmlEncoderTests extends AbstractEncoderTests<Jaxb2XmlEncoder>
 		assertThat(this.encoder.canEncode(forClass(Pojo.class), new MediaType("application", "foo+xml"))).isTrue();
 		assertThat(this.encoder.canEncode(forClass(Pojo.class), MediaType.APPLICATION_JSON)).isFalse();
 
-		assertThat(this.encoder.canEncode(forClass(Jaxb2XmlDecoderTests.TypePojo.class), MediaType.APPLICATION_XML)).isTrue();
+		assertThat(this.encoder.canEncode(forClass(TypePojo.class), MediaType.APPLICATION_XML)).isTrue();
 		assertThat(this.encoder.canEncode(forClass(getClass()), MediaType.APPLICATION_XML)).isFalse();
 
 		// SPR-15464

spring-web/src/test/java/org/springframework/http/codec/xml/TypePojo.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http.codec.xml;
+
+import org.springframework.lang.Nullable;
+
+/**
+ * @author Arjen Poutsma
+ */
+@jakarta.xml.bind.annotation.XmlType(name = "pojo")
+public class TypePojo {
+
+	private String foo;
+
+	private String bar;
+
+	public TypePojo() {
+	}
+
+	public TypePojo(String foo, String bar) {
+		this.foo = foo;
+		this.bar = bar;
+	}
+
+	public String getFoo() {
+		return this.foo;
+	}
+
+	public void setFoo(String foo) {
+		this.foo = foo;
+	}
+
+	public String getBar() {
+		return this.bar;
+	}
+
+	public void setBar(String bar) {
+		this.bar = bar;
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o instanceof TypePojo other) {
+			return this.foo.equals(other.foo) && this.bar.equals(other.bar);
+		}
+		return false;
+	}
+
+	@Override
+	public int hashCode() {
+		int result = this.foo.hashCode();
+		result = 31 * result + this.bar.hashCode();
+		return result;
+	}
+}

spring-web/src/test/java/org/springframework/http/codec/xml/jaxb/XmlRootElementWithName.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import jakarta.xml.bind.annotation.XmlRootElement;
 /**
  * @author Arjen Poutsma
  */
-@XmlRootElement(name = "name")
+@XmlRootElement(name = "name-type")
 public class XmlRootElementWithName {
 
 }

spring-web/src/test/java/org/springframework/http/codec/xml/jaxb/XmlRootElementWithNameAndNamespace.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import jakarta.xml.bind.annotation.XmlRootElement;
 /**
  * @author Arjen Poutsma
  */
-@XmlRootElement(name = "name", namespace = "namespace")
+@XmlRootElement(name = "name-type", namespace = "namespace-type")
 public class XmlRootElementWithNameAndNamespace {
 
 }

spring-web/src/test/java/org/springframework/http/codec/xml/jaxb/XmlTypeSeeAlso.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http.codec.xml.jaxb;
+
+import jakarta.xml.bind.annotation.XmlSeeAlso;
+
+/**
+ * @author Arjen Poutsma
+ */
+@jakarta.xml.bind.annotation.XmlType
+@XmlSeeAlso({XmlRootElementWithName.class, XmlRootElementWithNameAndNamespace.class})
+public class XmlTypeSeeAlso {
+
+}

spring-web/src/test/java/org/springframework/http/codec/xml/jaxb/XmlTypeWithName.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import jakarta.xml.bind.annotation.XmlType;
 /**
  * @author Arjen Poutsma
  */
-@XmlType(name = "name")
+@XmlType(name = "name-type")
 public class XmlTypeWithName {
 
 }

spring-web/src/test/java/org/springframework/http/codec/xml/jaxb/XmlTypeWithNameAndNamespace.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@ import jakarta.xml.bind.annotation.XmlType;
 /**
  * @author Arjen Poutsma
  */
-@XmlType(name = "name", namespace = "namespace")
+@XmlType(name = "name-type", namespace = "namespace-type")
 public class XmlTypeWithNameAndNamespace {
 
 }

spring-web/src/test/java/org/springframework/http/codec/xml/jaxb/package-info.java

@@ -1,2 +1,2 @@
-@jakarta.xml.bind.annotation.XmlSchema(namespace = "namespace")
+@jakarta.xml.bind.annotation.XmlSchema(namespace = "namespace-package")
 package org.springframework.http.codec.xml.jaxb;