Review nullability of spring-xml

See gh-1562

spring-xml/src/main/java/org/springframework/xml/XmlException.java

@@ -16,6 +16,8 @@
 
 package org.springframework.xml;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.NestedRuntimeException;
 
 /**
@@ -42,7 +44,7 @@ public abstract class XmlException extends NestedRuntimeException {
 	 * @param message the detail message
 	 * @param throwable the wrapped exception
 	 */
-	protected XmlException(String message, Throwable throwable) {
+	protected XmlException(@Nullable String message, Throwable throwable) {
 		super(message, throwable);
 	}
 

spring-xml/src/main/java/org/springframework/xml/dom/package-info.java

@@ -18,4 +18,7 @@
  * Provides classes that help with DOM: the Document Object Model. Mostly for internal use
  * by the framework.
  */
+@NullMarked
 package org.springframework.xml.dom;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/namespace/QNameUtils.java

@@ -18,6 +18,7 @@ package org.springframework.xml.namespace;
 
 import javax.xml.namespace.QName;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Node;
 
 import org.springframework.util.Assert;
@@ -37,7 +38,7 @@ public abstract class QNameUtils {
 	 * @param text the qualified name
 	 * @return {@code true} if valid, {@code false} otherwise
 	 */
-	public static boolean validateQName(String text) {
+	public static boolean validateQName(@Nullable String text) {
 		if (!StringUtils.hasLength(text)) {
 			return false;
 		}

spring-xml/src/main/java/org/springframework/xml/namespace/SimpleNamespaceContext.java

@@ -27,6 +27,8 @@ import java.util.Set;
 import javax.xml.XMLConstants;
 import javax.xml.namespace.NamespaceContext;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -59,7 +61,7 @@ public class SimpleNamespaceContext implements NamespaceContext {
 	}
 
 	@Override
-	public String getPrefix(String namespaceUri) {
+	public @Nullable String getPrefix(String namespaceUri) {
 		Iterator<String> iterator = getPrefixes(namespaceUri);
 		return iterator.hasNext() ? iterator.next() : null;
 	}

spring-xml/src/main/java/org/springframework/xml/namespace/package-info.java

@@ -18,4 +18,7 @@
  * Provides classes that help with XML Namespace processing. Mostly for internal use by
  * the framework.
  */
+@NullMarked
 package org.springframework.xml.namespace;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/package-info.java

@@ -18,4 +18,7 @@
  * Provides classes for XML handling: version detection and a base XML exception class.
  * Mostly for internal use by the framework.
  */
+@NullMarked
 package org.springframework.xml;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/sax/AbstractXmlReader.java

@@ -16,6 +16,7 @@
 
 package org.springframework.xml.sax;
 
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.ContentHandler;
 import org.xml.sax.DTDHandler;
 import org.xml.sax.EntityResolver;
@@ -38,18 +39,18 @@ import org.xml.sax.ext.LexicalHandler;
  */
 public abstract class AbstractXmlReader implements XMLReader {
 
-	private DTDHandler dtdHandler;
+	private @Nullable DTDHandler dtdHandler;
 
-	private ContentHandler contentHandler;
+	private @Nullable ContentHandler contentHandler;
 
-	private EntityResolver entityResolver;
+	private @Nullable EntityResolver entityResolver;
 
-	private ErrorHandler errorHandler;
+	private @Nullable ErrorHandler errorHandler;
 
-	private LexicalHandler lexicalHandler;
+	private @Nullable LexicalHandler lexicalHandler;
 
 	@Override
-	public ContentHandler getContentHandler() {
+	public @Nullable ContentHandler getContentHandler() {
 		return this.contentHandler;
 	}
 
@@ -64,12 +65,12 @@ public abstract class AbstractXmlReader implements XMLReader {
 	}
 
 	@Override
-	public DTDHandler getDTDHandler() {
+	public @Nullable DTDHandler getDTDHandler() {
 		return this.dtdHandler;
 	}
 
 	@Override
-	public EntityResolver getEntityResolver() {
+	public @Nullable EntityResolver getEntityResolver() {
 		return this.entityResolver;
 	}
 
@@ -79,7 +80,7 @@ public abstract class AbstractXmlReader implements XMLReader {
 	}
 
 	@Override
-	public ErrorHandler getErrorHandler() {
+	public @Nullable ErrorHandler getErrorHandler() {
 		return this.errorHandler;
 	}
 
@@ -88,7 +89,7 @@ public abstract class AbstractXmlReader implements XMLReader {
 		this.errorHandler = errorHandler;
 	}
 
-	protected LexicalHandler getLexicalHandler() {
+	protected @Nullable LexicalHandler getLexicalHandler() {
 		return this.lexicalHandler;
 	}
 
@@ -116,7 +117,7 @@ public abstract class AbstractXmlReader implements XMLReader {
 	 * {@code http://xml.org/sax/properties/lexical-handler}.
 	 */
 	@Override
-	public Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException {
+	public @Nullable Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException {
 		if ("http://xml.org/sax/properties/lexical-handler".equals(name)) {
 			return this.lexicalHandler;
 		}

spring-xml/src/main/java/org/springframework/xml/sax/SaxUtils.java

@@ -25,6 +25,7 @@ import javax.xml.parsers.SAXParserFactory;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.InputSource;
 import org.xml.sax.SAXException;
 import org.xml.sax.XMLReader;
@@ -76,7 +77,7 @@ public abstract class SaxUtils {
 	 * Retrieves the URL from the given resource as System ID. Returns {@code null} if it
 	 * cannot be opened.
 	 */
-	public static String getSystemId(Resource resource) {
+	public static @Nullable String getSystemId(Resource resource) {
 		try {
 			return new URI(resource.getURL().toExternalForm()).toString();
 		}

spring-xml/src/main/java/org/springframework/xml/sax/package-info.java

@@ -18,4 +18,7 @@
  * Provides classes that help with SAX: the Simple API for XML. Mostly for internal use by
  * the framework.
  */
+@NullMarked
 package org.springframework.xml.sax;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/transform/StringSource.java

@@ -22,6 +22,8 @@ import java.io.StringReader;
 
 import javax.xml.transform.stream.StreamSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -64,7 +66,7 @@ public class StringSource extends StreamSource {
 	 * @return {@code null}
 	 */
 	@Override
-	public InputStream getInputStream() {
+	public @Nullable InputStream getInputStream() {
 		return null;
 	}
 

spring-xml/src/main/java/org/springframework/xml/transform/TransformerHelper.java

@@ -23,6 +23,8 @@ import javax.xml.transform.TransformerConfigurationException;
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.TransformerFactory;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -34,9 +36,9 @@ import org.springframework.util.Assert;
  */
 public class TransformerHelper {
 
-	private volatile TransformerFactory transformerFactory;
+	private volatile @Nullable TransformerFactory transformerFactory;
 
-	private Class<? extends TransformerFactory> transformerFactoryClass;
+	private @Nullable Class<? extends TransformerFactory> transformerFactoryClass;
 
 	/**
 	 * Initializes a new instance of the {@code TransformerHelper}.
@@ -81,7 +83,8 @@ public class TransformerHelper {
 	 * @see #setTransformerFactoryClass
 	 * @see #getTransformerFactory()
 	 */
-	protected TransformerFactory newTransformerFactory(Class<? extends TransformerFactory> transformerFactoryClass) {
+	protected TransformerFactory newTransformerFactory(
+			@Nullable Class<? extends TransformerFactory> transformerFactoryClass) {
 		if (transformerFactoryClass != null) {
 			return TransformerFactoryUtils.newInstance(transformerFactoryClass);
 		}

spring-xml/src/main/java/org/springframework/xml/transform/TraxUtils.java

@@ -36,6 +36,7 @@ import javax.xml.transform.stax.StAXSource;
 import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Document;
 import org.w3c.dom.Node;
 import org.xml.sax.ContentHandler;
@@ -59,7 +60,7 @@ public abstract class TraxUtils {
 	 * @param source the DOM source
 	 * @return the document
 	 */
-	public static Document getDocument(DOMSource source) {
+	public static @Nullable Document getDocument(DOMSource source) {
 		Node node = source.getNode();
 		if (node instanceof Document) {
 			return (Document) node;

spring-xml/src/main/java/org/springframework/xml/transform/package-info.java

@@ -18,4 +18,7 @@
  * Provides classes that help with XML transformations. Mostly for internal use by the
  * framework.
  */
+@NullMarked
 package org.springframework.xml.transform;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/validation/Jaxp13ValidatorFactory.java

@@ -24,6 +24,7 @@ import javax.xml.transform.Source;
 import javax.xml.validation.Schema;
 import javax.xml.validation.Validator;
 
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.SAXException;
 import org.xml.sax.SAXParseException;
 
@@ -62,7 +63,8 @@ abstract class Jaxp13ValidatorFactory {
 		}
 
 		@Override
-		public SAXParseException[] validate(Source source, ValidationErrorHandler errorHandler) throws IOException {
+		public SAXParseException[] validate(Source source, @Nullable ValidationErrorHandler errorHandler)
+				throws IOException {
 			if (errorHandler == null) {
 				errorHandler = new DefaultValidationErrorHandler();
 			}

spring-xml/src/main/java/org/springframework/xml/validation/Jaxp15ValidatorFactory.java

@@ -27,6 +27,7 @@ import javax.xml.validation.Validator;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.SAXException;
 import org.xml.sax.SAXNotRecognizedException;
 import org.xml.sax.SAXNotSupportedException;
@@ -70,7 +71,8 @@ abstract class Jaxp15ValidatorFactory {
 		}
 
 		@Override
-		public SAXParseException[] validate(Source source, ValidationErrorHandler errorHandler) throws IOException {
+		public SAXParseException[] validate(Source source, @Nullable ValidationErrorHandler errorHandler)
+				throws IOException {
 			if (errorHandler == null) {
 				errorHandler = new DefaultValidationErrorHandler();
 			}

spring-xml/src/main/java/org/springframework/xml/validation/SchemaLoaderUtils.java

@@ -22,6 +22,7 @@ import javax.xml.transform.Source;
 import javax.xml.validation.Schema;
 import javax.xml.validation.SchemaFactory;
 
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.SAXException;
 import org.xml.sax.XMLReader;
 
@@ -91,7 +92,7 @@ public abstract class SchemaLoaderUtils {
 	 * Retrieves the URL from the given resource as System ID. Returns {@code null} if it
 	 * cannot be opened.
 	 */
-	public static String getSystemId(Resource resource) {
+	public static @Nullable String getSystemId(Resource resource) {
 		try {
 			return resource.getURL().toString();
 		}

spring-xml/src/main/java/org/springframework/xml/validation/XmlValidator.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 
 import javax.xml.transform.Source;
 
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.SAXParseException;
 
 /**
@@ -56,6 +57,6 @@ public interface XmlValidator {
 	 * @throws IOException if the {@code source} cannot be read
 	 * @throws XmlValidationException if the {@code source} cannot be validated
 	 */
-	SAXParseException[] validate(Source source, ValidationErrorHandler errorHandler) throws IOException;
+	SAXParseException[] validate(Source source, @Nullable ValidationErrorHandler errorHandler) throws IOException;
 
 }

spring-xml/src/main/java/org/springframework/xml/validation/package-info.java

@@ -18,4 +18,7 @@
  * Provides classes for XML validation in JAXP 1.0 and JAXP 1.3. Mostly for internal use
  * by the framework.
  */
+@NullMarked
 package org.springframework.xml.validation;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/xpath/AbstractXPathTemplate.java

@@ -16,12 +16,14 @@
 
 package org.springframework.xml.xpath;
 
+import java.util.Collections;
 import java.util.Map;
 
 import javax.xml.transform.Source;
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.dom.DOMResult;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
@@ -38,7 +40,7 @@ import org.springframework.xml.transform.TransformerObjectSupport;
  */
 public abstract class AbstractXPathTemplate extends TransformerObjectSupport implements XPathOperations {
 
-	private Map<String, String> namespaces;
+	private Map<String, String> namespaces = Collections.emptyMap();
 
 	/** Returns namespaces used in the XPath expression. */
 	public Map<String, String> getNamespaces() {
@@ -81,7 +83,7 @@ public abstract class AbstractXPathTemplate extends TransformerObjectSupport imp
 		}
 
 		@Override
-		public Object mapNode(Node node, int nodeNum) throws DOMException {
+		public @Nullable Object mapNode(Node node, int nodeNum) throws DOMException {
 			this.callbackHandler.processNode(node);
 			return null;
 		}

spring-xml/src/main/java/org/springframework/xml/xpath/JaxenXPathExpressionFactory.java

@@ -24,6 +24,7 @@ import org.jaxen.JaxenException;
 import org.jaxen.SimpleNamespaceContext;
 import org.jaxen.XPath;
 import org.jaxen.dom.DOMXPath;
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Node;
 
@@ -92,7 +93,7 @@ abstract class JaxenXPathExpressionFactory {
 		}
 
 		@Override
-		public Node evaluateAsNode(Node node) {
+		public @Nullable Node evaluateAsNode(Node node) {
 			try {
 				return (Node) this.xpath.selectSingleNode(node);
 			}
@@ -125,7 +126,7 @@ abstract class JaxenXPathExpressionFactory {
 		}
 
 		@Override
-		public String evaluateAsString(Node node) {
+		public @Nullable String evaluateAsString(Node node) {
 			try {
 				return this.xpath.stringValueOf(node);
 			}
@@ -148,7 +149,7 @@ abstract class JaxenXPathExpressionFactory {
 		}
 
 		@Override
-		public <T> T evaluateAsObject(Node context, NodeMapper<T> nodeMapper) throws XPathException {
+		public <T> @Nullable T evaluateAsObject(Node context, NodeMapper<T> nodeMapper) throws XPathException {
 			try {
 				Node result = (Node) this.xpath.selectSingleNode(context);
 				if (result != null) {

spring-xml/src/main/java/org/springframework/xml/xpath/JaxenXPathTemplate.java

@@ -18,6 +18,7 @@ package org.springframework.xml.xpath;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 
 import javax.xml.transform.Source;
 import javax.xml.transform.TransformerException;
@@ -26,6 +27,7 @@ import org.jaxen.JaxenException;
 import org.jaxen.SimpleNamespaceContext;
 import org.jaxen.XPath;
 import org.jaxen.dom.DOMXPath;
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -118,7 +120,8 @@ public class JaxenXPathTemplate extends AbstractXPathTemplate {
 	}
 
 	@Override
-	public <T> T evaluateAsObject(String expression, Source context, NodeMapper<T> nodeMapper) throws XPathException {
+	public <T> @Nullable T evaluateAsObject(String expression, Source context, NodeMapper<T> nodeMapper)
+			throws XPathException {
 		try {
 			XPath xpath = createXPath(expression);
 			Element element = getRootElement(context);
@@ -172,8 +175,9 @@ public class JaxenXPathTemplate extends AbstractXPathTemplate {
 
 	private XPath createXPath(String expression) throws JaxenException {
 		XPath xpath = new DOMXPath(expression);
-		if (getNamespaces() != null && !getNamespaces().isEmpty()) {
-			xpath.setNamespaceContext(new SimpleNamespaceContext(getNamespaces()));
+		Map<String, String> namespaces = getNamespaces();
+		if (!namespaces.isEmpty()) {
+			xpath.setNamespaceContext(new SimpleNamespaceContext(namespaces));
 		}
 		return xpath;
 	}

spring-xml/src/main/java/org/springframework/xml/xpath/Jaxp13XPathExpressionFactory.java

@@ -26,6 +26,7 @@ import javax.xml.xpath.XPathConstants;
 import javax.xml.xpath.XPathExpressionException;
 import javax.xml.xpath.XPathFactory;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
@@ -153,18 +154,13 @@ abstract class Jaxp13XPathExpressionFactory {
 		}
 
 		@Override
-		public <T> T evaluateAsObject(Node node, NodeMapper<T> nodeMapper) throws XPathException {
+		public <T> @Nullable T evaluateAsObject(Node node, NodeMapper<T> nodeMapper) throws XPathException {
 			Node result = (Node) evaluate(node, XPathConstants.NODE);
-			if (result != null) {
-				try {
-					return nodeMapper.mapNode(result, 0);
-				}
-				catch (DOMException ex) {
-					throw new XPathException("Mapping resulted in DOMException", ex);
-				}
+			try {
+				return nodeMapper.mapNode(result, 0);
 			}
-			else {
-				return null;
+			catch (DOMException ex) {
+				throw new XPathException("Mapping resulted in DOMException", ex);
 			}
 		}
 

spring-xml/src/main/java/org/springframework/xml/xpath/Jaxp13XPathTemplate.java

@@ -20,6 +20,7 @@ import java.io.InputStream;
 import java.io.Reader;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 
 import javax.xml.namespace.QName;
 import javax.xml.stream.XMLEventReader;
@@ -34,6 +35,7 @@ import javax.xml.xpath.XPathExpressionException;
 import javax.xml.xpath.XPathFactory;
 import javax.xml.xpath.XPathFactoryConfigurationException;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
@@ -81,16 +83,18 @@ public class Jaxp13XPathTemplate extends AbstractXPathTemplate {
 	}
 
 	@Override
-	public Node evaluateAsNode(String expression, Source context) throws XPathException {
+	public @Nullable Node evaluateAsNode(String expression, Source context) throws XPathException {
 		return (Node) evaluate(expression, context, XPathConstants.NODE);
 	}
 
 	@Override
 	public List<Node> evaluateAsNodeList(String expression, Source context) throws XPathException {
 		NodeList result = (NodeList) evaluate(expression, context, XPathConstants.NODESET);
-		List<Node> nodes = new ArrayList<>(result.getLength());
-		for (int i = 0; i < result.getLength(); i++) {
-			nodes.add(result.item(i));
+		List<Node> nodes = new ArrayList<>();
+		if (result != null) {
+			for (int i = 0; i < result.getLength(); i++) {
+				nodes.add(result.item(i));
+			}
 		}
 		return nodes;
 	}
@@ -102,46 +106,45 @@ public class Jaxp13XPathTemplate extends AbstractXPathTemplate {
 	}
 
 	@Override
-	public String evaluateAsString(String expression, Source context) throws XPathException {
+	public @Nullable String evaluateAsString(String expression, Source context) throws XPathException {
 		return (String) evaluate(expression, context, XPathConstants.STRING);
 	}
 
 	@Override
-	public <T> T evaluateAsObject(String expression, Source context, NodeMapper<T> nodeMapper) throws XPathException {
+	public <T> @Nullable T evaluateAsObject(String expression, Source context, NodeMapper<T> nodeMapper)
+			throws XPathException {
 		Node node = evaluateAsNode(expression, context);
-		if (node != null) {
-			try {
-				return nodeMapper.mapNode(node, 0);
-			}
-			catch (DOMException ex) {
-				throw new XPathException("Mapping resulted in DOMException", ex);
-			}
+		try {
+			return (node != null) ? nodeMapper.mapNode(node, 0) : null;
 		}
-		else {
-			return null;
+		catch (DOMException ex) {
+			throw new XPathException("Mapping resulted in DOMException", ex);
 		}
 	}
 
 	@Override
 	public <T> List<T> evaluate(String expression, Source context, NodeMapper<T> nodeMapper) throws XPathException {
 		NodeList nodes = (NodeList) evaluate(expression, context, XPathConstants.NODESET);
-		List<T> results = new ArrayList<>(nodes.getLength());
-		for (int i = 0; i < nodes.getLength(); i++) {
-			try {
-				results.add(nodeMapper.mapNode(nodes.item(i), i));
-			}
-			catch (DOMException ex) {
-				throw new XPathException("Mapping resulted in DOMException", ex);
+		List<T> results = new ArrayList<>();
+		if (nodes != null) {
+			for (int i = 0; i < nodes.getLength(); i++) {
+				try {
+					results.add(nodeMapper.mapNode(nodes.item(i), i));
+				}
+				catch (DOMException ex) {
+					throw new XPathException("Mapping resulted in DOMException", ex);
+				}
 			}
 		}
 		return results;
 	}
 
-	private Object evaluate(String expression, Source context, QName returnType) throws XPathException {
+	private @Nullable Object evaluate(String expression, Source context, QName returnType) throws XPathException {
 		XPath xpath = createXPath();
-		if (getNamespaces() != null && !getNamespaces().isEmpty()) {
+		Map<String, String> namespaces = getNamespaces();
+		if (!namespaces.isEmpty()) {
 			SimpleNamespaceContext namespaceContext = new SimpleNamespaceContext();
-			namespaceContext.setBindings(getNamespaces());
+			namespaceContext.setBindings(namespaces);
 			xpath.setNamespaceContext(namespaceContext);
 		}
 		try {
@@ -174,7 +177,7 @@ public class Jaxp13XPathTemplate extends AbstractXPathTemplate {
 
 		private final TransformerHelper transformerHelper = new TransformerHelper();
 
-		private Object result;
+		private @Nullable Object result;
 
 		private EvaluationCallback(XPath xpath, String expression, QName returnType) {
 			this.xpath = xpath;

spring-xml/src/main/java/org/springframework/xml/xpath/NodeMapper.java

@@ -16,6 +16,7 @@
 
 package org.springframework.xml.xpath;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Node;
 
@@ -42,6 +43,6 @@ public interface NodeMapper<T> {
 	 * @return object for the current node
 	 * @throws DOMException in case of DOM errors
 	 */
-	T mapNode(Node node, int nodeNum) throws DOMException;
+	@Nullable T mapNode(Node node, int nodeNum) throws DOMException;
 
 }

spring-xml/src/main/java/org/springframework/xml/xpath/XPathException.java

@@ -16,6 +16,8 @@
 
 package org.springframework.xml.xpath;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.xml.XmlException;
 
 /**
@@ -42,7 +44,7 @@ public class XPathException extends XmlException {
 	 * @param message the detail message
 	 * @param throwable the wrapped exception
 	 */
-	public XPathException(String message, Throwable throwable) {
+	public XPathException(@Nullable String message, Throwable throwable) {
 		super(message, throwable);
 	}
 

spring-xml/src/main/java/org/springframework/xml/xpath/XPathExpression.java

@@ -18,6 +18,7 @@ package org.springframework.xml.xpath;
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Node;
 
 /**
@@ -58,7 +59,7 @@ public interface XPathExpression {
 	 * @throws XPathException in case of XPath errors
 	 * @see <a href="http://www.w3.org/TR/xpath#node-sets">XPath specification</a>
 	 */
-	Node evaluateAsNode(Node node) throws XPathException;
+	@Nullable Node evaluateAsNode(Node node) throws XPathException;
 
 	/**
 	 * Evaluates the given expression, and returns all {@link Node} objects that conform
@@ -98,7 +99,7 @@ public interface XPathExpression {
 	 * @see <a href="http://www.w3.org/TR/xpath/#function-string">XPath specification -
 	 * string() function</a>
 	 */
-	String evaluateAsString(Node node) throws XPathException;
+	@Nullable String evaluateAsString(Node node) throws XPathException;
 
 	/**
 	 * Evaluates the given expression, mapping a single {@link Node} result to a Java
@@ -109,7 +110,7 @@ public interface XPathExpression {
 	 * @throws XPathException in case of XPath errors
 	 * @see <a href="http://www.w3.org/TR/xpath#node-sets">XPath specification</a>
 	 */
-	<T> T evaluateAsObject(Node node, NodeMapper<T> nodeMapper) throws XPathException;
+	<T> @Nullable T evaluateAsObject(Node node, NodeMapper<T> nodeMapper) throws XPathException;
 
 	/**
 	 * Evaluates the given expression, mapping each result {@link Node} objects to a Java

spring-xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactory.java

@@ -21,6 +21,7 @@ import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.Assert;
 
@@ -61,7 +62,7 @@ public abstract class XPathExpressionFactory {
 	 * @throws IllegalStateException if neither JAXP 1.3+, or Jaxen are available
 	 * @throws XPathParseException if the given expression cannot be parsed
 	 */
-	public static XPathExpression createXPathExpression(String expression, Map<String, String> namespaces)
+	public static XPathExpression createXPathExpression(String expression, @Nullable Map<String, String> namespaces)
 			throws IllegalStateException, XPathParseException {
 		Assert.hasLength(expression, "expression is empty");
 		if (namespaces == null) {

spring-xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactoryBean.java

@@ -36,10 +36,13 @@ import org.springframework.util.CollectionUtils;
  */
 public class XPathExpressionFactoryBean implements FactoryBean<XPathExpression>, InitializingBean {
 
+	@SuppressWarnings("NullAway.Init")
 	private Map<String, String> namespaces;
 
+	@SuppressWarnings("NullAway.Init")
 	private String expressionString;
 
+	@SuppressWarnings("NullAway.Init")
 	private XPathExpression expression;
 
 	/** Sets the XPath expression. Setting this property is required. */

spring-xml/src/main/java/org/springframework/xml/xpath/XPathOperations.java

@@ -20,6 +20,7 @@ import java.util.List;
 
 import javax.xml.transform.Source;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Node;
 
 /**
@@ -65,7 +66,7 @@ public interface XPathOperations {
 	 * @throws XPathException in case of XPath errors
 	 * @see <a href="http://www.w3.org/TR/xpath#node-sets">XPath specification</a>
 	 */
-	Node evaluateAsNode(String expression, Source context) throws XPathException;
+	@Nullable Node evaluateAsNode(String expression, Source context) throws XPathException;
 
 	/**
 	 * Evaluates the given expression as a list of {@link Node} objects. Returns the
@@ -108,7 +109,7 @@ public interface XPathOperations {
 	 * @see <a href="http://www.w3.org/TR/xpath/#function-string">XPath specification -
 	 * string() function</a>
 	 */
-	String evaluateAsString(String expression, Source context) throws XPathException;
+	@Nullable String evaluateAsString(String expression, Source context) throws XPathException;
 
 	/**
 	 * Evaluates the given expression, mapping a single {@link Node} result to a Java
@@ -120,7 +121,7 @@ public interface XPathOperations {
 	 * @throws XPathException in case of XPath errors
 	 * @see <a href="http://www.w3.org/TR/xpath#node-sets">XPath specification</a>
 	 */
-	<T> T evaluateAsObject(String expression, Source context, NodeMapper<T> nodeMapper) throws XPathException;
+	<T> @Nullable T evaluateAsObject(String expression, Source context, NodeMapper<T> nodeMapper) throws XPathException;
 
 	/**
 	 * Evaluates the given expression, mapping each result {@link Node} objects to a Java

spring-xml/src/main/java/org/springframework/xml/xpath/package-info.java

@@ -18,4 +18,7 @@
  * Provides XPathTemplate implementations, and various classes for XPath evaluation using
  * JAXP 1.3, and Jaxen.
  */
+@NullMarked
 package org.springframework.xml.xpath;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/xsd/SimpleXsdSchema.java

@@ -24,6 +24,7 @@ import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.transform.Source;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.xml.sax.SAXException;
@@ -56,9 +57,9 @@ public class SimpleXsdSchema implements XsdSchema, InitializingBean {
 
 	private static final QName SCHEMA_NAME = new QName(SCHEMA_NAMESPACE, "schema", "xsd");
 
-	private Resource xsdResource;
+	private @Nullable Resource xsdResource;
 
-	private String targetNamespace;
+	private @Nullable String targetNamespace;
 
 	static {
 		documentBuilderFactory.setNamespaceAware(true);
@@ -127,20 +128,21 @@ public class SimpleXsdSchema implements XsdSchema, InitializingBean {
 		Assert.notNull(this.xsdResource, "'xsd' is required");
 		Assert.isTrue(this.xsdResource.exists(), "xsd '" + this.xsdResource + "' does not exist");
 		DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
-		loadSchema(documentBuilder);
+		this.targetNamespace = loadSchema(documentBuilder, this.xsdResource);
 	}
 
-	private void loadSchema(DocumentBuilder documentBuilder) throws SAXException, IOException {
-		Document schemaDocument = documentBuilder.parse(SaxUtils.createInputSource(this.xsdResource));
+	private static String loadSchema(DocumentBuilder documentBuilder, Resource resource)
+			throws SAXException, IOException {
+		Document schemaDocument = documentBuilder.parse(SaxUtils.createInputSource(resource));
 		Element schemaElement = schemaDocument.getDocumentElement();
-		Assert.isTrue(SCHEMA_NAME.getLocalPart().equals(schemaElement.getLocalName()), this.xsdResource
-				+ " has invalid root element : [" + schemaElement.getLocalName() + "] instead of [schema]");
+		Assert.isTrue(SCHEMA_NAME.getLocalPart().equals(schemaElement.getLocalName()),
+				resource + " has invalid root element : [" + schemaElement.getLocalName() + "] instead of [schema]");
 		Assert.isTrue(SCHEMA_NAME.getNamespaceURI().equals(schemaElement.getNamespaceURI()),
-				this.xsdResource + " has invalid root element: [" + schemaElement.getNamespaceURI() + "] instead of ["
+				resource + " has invalid root element: [" + schemaElement.getNamespaceURI() + "] instead of ["
 						+ SCHEMA_NAME.getNamespaceURI() + "]");
 		String targetNamespace = schemaElement.getAttribute("targetNamespace");
-		Assert.hasText(targetNamespace, this.xsdResource + " has no targetNamespace");
-		this.targetNamespace = targetNamespace;
+		Assert.hasText(targetNamespace, resource + " has no targetNamespace");
+		return targetNamespace;
 	}
 
 	public String toString() {

spring-xml/src/main/java/org/springframework/xml/xsd/XsdSchemaException.java

@@ -16,6 +16,8 @@
 
 package org.springframework.xml.xsd;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.xml.XmlException;
 
 /**
@@ -32,7 +34,7 @@ public class XsdSchemaException extends XmlException {
 		super(message);
 	}
 
-	public XsdSchemaException(String message, Throwable throwable) {
+	public XsdSchemaException(@Nullable String message, Throwable throwable) {
 		super(message, throwable);
 	}
 

spring-xml/src/main/java/org/springframework/xml/xsd/commons/CommonsXsdSchema.java

@@ -31,6 +31,7 @@ import javax.xml.transform.stream.StreamSource;
 import org.apache.ws.commons.schema.XmlSchema;
 import org.apache.ws.commons.schema.XmlSchemaCollection;
 import org.apache.ws.commons.schema.XmlSchemaSerializer;
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Document;
 
 import org.springframework.beans.BeanInstantiationException;
@@ -54,7 +55,7 @@ public class CommonsXsdSchema implements XsdSchema {
 
 	private final XmlSchema schema;
 
-	private final XmlSchemaCollection collection;
+	private final @Nullable XmlSchemaCollection collection;
 
 	/**
 	 * Create a new instance of the {@code CommonsXsdSchema} class with the specified
@@ -74,7 +75,7 @@ public class CommonsXsdSchema implements XsdSchema {
 	 * {@code null}
 	 * @throws IllegalArgumentException if the supplied {@code schema} is {@code null}
 	 */
-	protected CommonsXsdSchema(XmlSchema schema, XmlSchemaCollection collection) {
+	protected CommonsXsdSchema(XmlSchema schema, @Nullable XmlSchemaCollection collection) {
 		Assert.notNull(schema, "'schema' must not be null");
 		this.schema = schema;
 		this.collection = collection;

spring-xml/src/main/java/org/springframework/xml/xsd/commons/CommonsXsdSchemaCollection.java

@@ -32,6 +32,7 @@ import org.apache.ws.commons.schema.XmlSchemaInclude;
 import org.apache.ws.commons.schema.XmlSchemaObject;
 import org.apache.ws.commons.schema.resolver.DefaultURIResolver;
 import org.apache.ws.commons.schema.resolver.URIResolver;
+import org.jspecify.annotations.Nullable;
 import org.xml.sax.InputSource;
 
 import org.springframework.beans.factory.InitializingBean;
@@ -74,7 +75,7 @@ public class CommonsXsdSchemaCollection implements XsdSchemaCollection, Initiali
 
 	private URIResolver uriResolver = new ClasspathUriResolver();
 
-	private ResourceLoader resourceLoader;
+	private @Nullable ResourceLoader resourceLoader;
 
 	/**
 	 * Constructs a new, empty instance of the {@code CommonsXsdSchemaCollection}.
@@ -82,6 +83,7 @@ public class CommonsXsdSchemaCollection implements XsdSchemaCollection, Initiali
 	 * A subsequent call to the {@link #setXsds(Resource[])} is required.
 	 */
 	public CommonsXsdSchemaCollection() {
+		this(new Resource[0]);
 	}
 
 	/**

spring-xml/src/main/java/org/springframework/xml/xsd/commons/CommonsXsdSchemaException.java

@@ -16,6 +16,8 @@
 
 package org.springframework.xml.xsd.commons;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.xml.xsd.XsdSchemaException;
 
 /**
@@ -31,7 +33,7 @@ public class CommonsXsdSchemaException extends XsdSchemaException {
 		super(message);
 	}
 
-	public CommonsXsdSchemaException(String message, Throwable exception) {
+	public CommonsXsdSchemaException(@Nullable String message, Throwable exception) {
 		super(message, exception);
 	}
 

spring-xml/src/main/java/org/springframework/xml/xsd/commons/package-info.java

@@ -18,4 +18,7 @@
  * Contains a implementation of the {@code XsdSchema} interfaces that uses Apache
  * WS-Commons XML Schema.
  */
+@NullMarked
 package org.springframework.xml.xsd.commons;
+
+import org.jspecify.annotations.NullMarked;

spring-xml/src/main/java/org/springframework/xml/xsd/package-info.java

@@ -18,4 +18,7 @@
  * Provides an abstraction over XSD XML schemas. Contains the {@code XsdSchema} and
  * related interfaces.
  */
+@NullMarked
 package org.springframework.xml.xsd;
+
+import org.jspecify.annotations.NullMarked;