Add JSpecify Nullability to the xml package

* Tests were updated
* Test XML files updated to handle non nullable attributes and parameters
* In some cases I reformatted the whole xml file vs the changed section.   If this is a problem I'll undo.
* In many circumstances the chances of having null, should not happen, so `Objects.requireNonNull` was used.  But wonder if we should use Assert.state and have a message.   Thoughts?

Author: cppwfs

spring-integration-cassandra/src/main/java/org/springframework/integration/cassandra/config/xml/CassandraParserUtils.java

@@ -18,6 +18,7 @@
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -91,7 +92,7 @@ public static void processOutboundTypeAttributes(Element element, ParserContext
 
 	}
 
-	public static boolean areMutuallyExclusive(String query, BeanDefinition statementExpressionDef,
+	public static boolean areMutuallyExclusive(@Nullable String query, @Nullable BeanDefinition statementExpressionDef,
 			String ingestQuery) {
 
 		return !StringUtils.hasText(query) && statementExpressionDef == null && !StringUtils.hasText(ingestQuery)

spring-integration-core/src/main/java/org/springframework/integration/config/annotation/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting annotation-based configuration.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.config.annotation;

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractChannelAdapterParser.java

@@ -16,6 +16,7 @@
 
 package org.springframework.integration.config.xml;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.MutablePropertyValues;
@@ -62,6 +63,7 @@ else if (!StringUtils.hasText(id)) {
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	protected final AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
 		String channelName = element.getAttribute("channel");
 		if (!StringUtils.hasText(channelName)) {
@@ -88,7 +90,7 @@ protected final AbstractBeanDefinition parseInternal(Element element, ParserCont
 		return beanDefinition;
 	}
 
-	private String createDirectChannel(Element element, ParserContext parserContext) {
+	private @Nullable String createDirectChannel(Element element, ParserContext parserContext) {
 		if (parserContext.isNested()) {
 			return null;
 		}

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractChannelParser.java

@@ -16,6 +16,9 @@
 
 package org.springframework.integration.config.xml;
 
+import java.util.Objects;
+
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.aop.scope.ScopedProxyUtils;
@@ -44,7 +47,7 @@ public abstract class AbstractChannelParser extends AbstractBeanDefinitionParser
 	@Override
 	protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
 		BeanDefinitionBuilder builder = this.buildBeanDefinition(element, parserContext);
-		AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
+		AbstractBeanDefinition beanDefinition = Objects.requireNonNull(builder).getBeanDefinition();
 		Element interceptorsElement = DomUtils.getChildElementByTagName(element, "interceptors");
 		String datatypeAttr = element.getAttribute("datatype");
 		String messageConverter = element.getAttribute("message-converter");
@@ -107,6 +110,6 @@ protected void registerBeanDefinition(BeanDefinitionHolder definition, BeanDefin
 	 * @param parserContext The parser context.
 	 * @return The bean definition builder.
 	 */
-	protected abstract BeanDefinitionBuilder buildBeanDefinition(Element element, ParserContext parserContext);
+	protected abstract @Nullable BeanDefinitionBuilder buildBeanDefinition(Element element, ParserContext parserContext);
 
 }

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractConsumerEndpointParser.java

@@ -18,7 +18,9 @@
 
 import java.util.Collection;
 import java.util.List;
+import java.util.Objects;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.factory.BeanDefinitionStoreException;
@@ -78,16 +80,16 @@ protected String resolveId(Element element, AbstractBeanDefinition definition, P
 	 * @param parserContext The parser context.
 	 * @return The bean definition builder.
 	 */
-	protected abstract BeanDefinitionBuilder parseHandler(Element element, ParserContext parserContext);
+	protected abstract @Nullable BeanDefinitionBuilder parseHandler(Element element, ParserContext parserContext);
 
 	protected String getInputChannelAttributeName() {
 		return "input-channel";
 	}
 
 	@Override
-	protected final AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
+	protected final @Nullable AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
 		BeanDefinitionBuilder handlerBuilder = parseHandler(element, parserContext);
-		IntegrationNamespaceUtils.setValueIfAttributeDefined(handlerBuilder, element, "output-channel",
+		IntegrationNamespaceUtils.setValueIfAttributeDefined(Objects.requireNonNull(handlerBuilder), element, "output-channel",
 				"outputChannelName");
 		IntegrationNamespaceUtils.setValueIfAttributeDefined(handlerBuilder, element, "order");
 
@@ -140,9 +142,9 @@ protected final AbstractBeanDefinition parseInternal(Element element, ParserCont
 
 		String handlerBeanName =
 				BeanDefinitionReaderUtils.generateBeanName(handlerBeanDefinition, parserContext.getRegistry());
-		String[] handlerAlias = IntegrationNamespaceUtils.generateAlias(element);
 		parserContext.registerBeanComponent(
-				new BeanComponentDefinition(handlerBeanDefinition, handlerBeanName, handlerAlias));
+				new BeanComponentDefinition(handlerBeanDefinition, handlerBeanName,
+						IntegrationNamespaceUtils.generateAlias(element)));
 
 		builder.addPropertyReference("handler", handlerBeanName);
 
@@ -194,13 +196,11 @@ private void registerChannelForCreation(ParserContext parserContext, String inpu
 			if (vh == null) { //although it should never happen if it does we can fix it
 				caValues.addIndexedArgumentValue(0, new ManagedSet<String>());
 			}
-
 			@SuppressWarnings("unchecked")
 			Collection<String> channelCandidateNames =
-					(Collection<String>) caValues.getArgumentValue(0, Collection.class)
+					(Collection<String>) Objects.requireNonNull(caValues.getArgumentValue(0, Collection.class))
 							.getValue(); // NOSONAR see comment above
-			channelCandidateNames.add(inputChannelName); // NOSONAR
-
+			Objects.requireNonNull(channelCandidateNames).add(inputChannelName); // NOSONAR
 			consumerEndpointBuilder.addDependsOn(IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME);
 		}
 		else {

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractCorrelatingMessageHandlerParser.java

@@ -16,6 +16,7 @@
 
 package org.springframework.integration.config.xml;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.BeanMetadataElement;
@@ -65,7 +66,7 @@ public abstract class AbstractCorrelatingMessageHandlerParser extends AbstractCo
 
 	private static final String RELEASE_LOCK = "release-lock-before-send";
 
-	protected void doParse(BeanDefinitionBuilder builder, Element element, BeanMetadataElement processor,
+	protected void doParse(BeanDefinitionBuilder builder, Element element, @Nullable BeanMetadataElement processor,
 			ParserContext parserContext) {
 		IntegrationNamespaceUtils.injectPropertyWithAdapter(CORRELATION_STRATEGY_REF_ATTRIBUTE,
 				CORRELATION_STRATEGY_METHOD_ATTRIBUTE,

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractDelegatingConsumerEndpointParser.java

@@ -16,6 +16,7 @@
 
 package org.springframework.integration.config.xml;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -39,7 +40,7 @@
 abstract class AbstractDelegatingConsumerEndpointParser extends AbstractConsumerEndpointParser {
 
 	@Override
-	protected final BeanDefinitionBuilder parseHandler(Element element, ParserContext parserContext) {
+	protected final @Nullable BeanDefinitionBuilder parseHandler(Element element, ParserContext parserContext) {
 		Object source = parserContext.extractSource(element);
 		BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(this.getFactoryBeanClassName());
 		BeanComponentDefinition innerDefinition = IntegrationNamespaceUtils.parseInnerHandlerDefinition(element,
@@ -87,9 +88,9 @@ else if (!this.hasDefaultOption()) {
 		return builder;
 	}
 
-	private void innerDefinition(Element element, ParserContext parserContext, Object source,
+	private void innerDefinition(Element element, ParserContext parserContext, @Nullable Object source,
 			BeanDefinitionBuilder builder, BeanComponentDefinition innerDefinition, boolean hasRef,
-			boolean hasExpression, Element expressionElement) {
+			boolean hasExpression, @Nullable Element expressionElement) {
 		if (hasRef || hasExpression || expressionElement != null) {
 			parserContext.getReaderContext().error(
 					"Neither 'ref' nor 'expression' are permitted when an inner bean (<bean/>) is configured on element " +
@@ -98,9 +99,9 @@ private void innerDefinition(Element element, ParserContext parserContext, Objec
 		builder.addPropertyValue("targetObject", innerDefinition);
 	}
 
-	private void scriptElement(Element element, ParserContext parserContext, Object source,
+	private void scriptElement(Element element, ParserContext parserContext, @Nullable Object source,
 			BeanDefinitionBuilder builder, boolean hasRef, boolean hasExpression, Element scriptElement,
-			Element expressionElement) {
+			@Nullable Element expressionElement) {
 		if (hasRef || hasExpression || expressionElement != null) {
 			parserContext.getReaderContext().error(
 					"Neither 'ref' nor 'expression' are permitted when an inner script element is configured on element " +
@@ -110,7 +111,7 @@ private void scriptElement(Element element, ParserContext parserContext, Object
 		builder.addPropertyValue("targetObject", scriptBeanDefinition);
 	}
 
-	private void expressionElement(Element element, ParserContext parserContext, Object source,
+	private void expressionElement(Element element, ParserContext parserContext, @Nullable Object source,
 			BeanDefinitionBuilder builder, boolean hasRef, boolean hasExpression, Element expressionElement) {
 		if (hasRef || hasExpression) {
 			parserContext.getReaderContext().error(
@@ -126,9 +127,9 @@ private void expressionElement(Element element, ParserContext parserContext, Obj
 		builder.addPropertyValue("expression", dynamicExpressionBuilder.getBeanDefinition());
 	}
 
-	private void methodAttribute(Element element, ParserContext parserContext, Object source,
-			BeanDefinitionBuilder builder, BeanComponentDefinition innerDefinition, boolean hasRef,
-			boolean hasExpression, Element expressionElement) {
+	private void methodAttribute(Element element, ParserContext parserContext, @Nullable Object source,
+			BeanDefinitionBuilder builder, @Nullable BeanComponentDefinition innerDefinition, boolean hasRef,
+			boolean hasExpression, @Nullable Element expressionElement) {
 		String method = element.getAttribute(METHOD_ATTRIBUTE);
 		if (StringUtils.hasText(method)) {
 			if (hasExpression || expressionElement != null) {

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractIntegrationNamespaceHandler.java

@@ -18,6 +18,7 @@
 
 import java.util.concurrent.atomic.AtomicBoolean;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -47,7 +48,7 @@ public abstract class AbstractIntegrationNamespaceHandler extends NamespaceHandl
 	private final AtomicBoolean initialized = new AtomicBoolean();
 
 	@Override
-	public final BeanDefinition parse(Element element, ParserContext parserContext) {
+	public final @Nullable BeanDefinition parse(Element element, ParserContext parserContext) {
 		if (!this.initialized.getAndSet(true)) {
 			BeanDefinitionRegistry registry = parserContext.getRegistry();
 			new IntegrationRegistrar().registerBeanDefinitions(null, registry);

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractOutboundChannelAdapterParser.java

@@ -16,6 +16,7 @@
 
 package org.springframework.integration.config.xml;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -82,7 +83,7 @@ protected AbstractBeanDefinition doParse(Element element, ParserContext parserCo
 	}
 
 	private void configureRequestHandlerAdviceChain(Element element, ParserContext parserContext,
-			BeanDefinition handlerBeanDefinition, BeanDefinitionBuilder consumerBuilder) {
+			BeanDefinition handlerBeanDefinition, @Nullable BeanDefinitionBuilder consumerBuilder) {
 		Element txElement = DomUtils.getChildElementByTagName(element, "transactional");
 		Element adviceChainElement = DomUtils.getChildElementByTagName(element,
 				IntegrationNamespaceUtils.REQUEST_HANDLER_ADVICE_CHAIN);

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractPollingInboundChannelAdapterParser.java

@@ -16,6 +16,7 @@
 
 package org.springframework.integration.config.xml;
 
+import org.jspecify.annotations.Nullable;
 import org.w3c.dom.Element;
 
 import org.springframework.beans.BeanMetadataElement;
@@ -59,6 +60,7 @@ else if (source instanceof RuntimeBeanReference runtimeBeanReference) {
 		}
 		else {
 			parserContext.getReaderContext().error("Wrong 'source' type: must be 'BeanDefinition' or 'RuntimeBeanReference'", source);
+			throw new IllegalStateException("sourceBeanName must not be null");
 		}
 
 		adapterBuilder.addPropertyReference("source", sourceBeanName);
@@ -79,6 +81,6 @@ else if (source instanceof RuntimeBeanReference runtimeBeanReference) {
 	 * @param parserContext The parser context.
 	 * @return The bean metadata element.
 	 */
-	protected abstract BeanMetadataElement parseSource(Element element, ParserContext parserContext);
+	protected abstract @Nullable BeanMetadataElement parseSource(Element element, ParserContext parserContext);
 
 }