Nullability refinements and related polishing

See gh-32475

spring-aop/src/main/java/org/springframework/aop/support/AopUtils.java

@@ -364,18 +364,18 @@ public abstract class AopUtils {
 		}
 	}
 
+
 	/**
 	 * Inner class to avoid a hard dependency on Kotlin at runtime.
 	 */
 	private static class KotlinDelegate {
 
-		public static Publisher<?> invokeSuspendingFunction(Method method, Object target, Object... args) {
+		public static Publisher<?> invokeSuspendingFunction(Method method, @Nullable Object target, Object... args) {
 			Continuation<?> continuation = (Continuation<?>) args[args.length -1];
 			Assert.state(continuation != null, "No Continuation available");
 			CoroutineContext context = continuation.getContext().minusKey(Job.Key);
 			return CoroutinesUtils.invokeSuspendingFunction(context, method, target, args);
 		}
-
 	}
 
 }

spring-beans/src/main/java/org/springframework/beans/AbstractNestablePropertyAccessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -845,8 +845,10 @@ public abstract class AbstractNestablePropertyAccessor extends AbstractPropertyA
 	 * @return the PropertyAccessor instance, either cached or newly created
 	 */
 	private AbstractNestablePropertyAccessor getNestedPropertyAccessor(String nestedProperty) {
-		if (this.nestedPropertyAccessors == null) {
+		Map<String, AbstractNestablePropertyAccessor> nestedAccessors = this.nestedPropertyAccessors;
-			this.nestedPropertyAccessors = new HashMap<>();
+		if (nestedAccessors == null) {
+			nestedAccessors = new HashMap<>();
+			this.nestedPropertyAccessors = nestedAccessors;
 		}
 		// Get value of bean property.
 		PropertyTokenHolder tokens = getPropertyNameTokens(nestedProperty);
@@ -862,7 +864,7 @@ public abstract class AbstractNestablePropertyAccessor extends AbstractPropertyA
 		}
 
 		// Lookup cached sub-PropertyAccessor, create new one if not found.
-		AbstractNestablePropertyAccessor nestedPa = this.nestedPropertyAccessors.get(canonicalName);
+		AbstractNestablePropertyAccessor nestedPa = nestedAccessors.get(canonicalName);
 		if (nestedPa == null || nestedPa.getWrappedInstance() != ObjectUtils.unwrapOptional(value)) {
 			if (logger.isTraceEnabled()) {
 				logger.trace("Creating new nested " + getClass().getSimpleName() + " for property '" + canonicalName + "'");
@@ -871,7 +873,7 @@ public abstract class AbstractNestablePropertyAccessor extends AbstractPropertyA
 			// Inherit all type-specific PropertyEditors.
 			copyDefaultEditorsTo(nestedPa);
 			copyCustomEditorsTo(nestedPa, canonicalName);
-			this.nestedPropertyAccessors.put(canonicalName, nestedPa);
+			nestedAccessors.put(canonicalName, nestedPa);
 		}
 		else {
 			if (logger.isTraceEnabled()) {

spring-beans/src/main/java/org/springframework/beans/factory/groovy/GroovyBeanDefinitionReader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -54,6 +54,7 @@ import org.springframework.core.io.DescriptiveResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.EncodedResource;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
@@ -250,6 +251,7 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 		@SuppressWarnings("serial")
 		Closure<Object> beans = new Closure<>(this) {
 			@Override
+			@Nullable
 			public Object call(Object... args) {
 				invokeBeanDefiningClosure((Closure<?>) args[0]);
 				return null;
@@ -425,6 +427,7 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 
 	private boolean addDeferredProperty(String property, Object newValue) {
 		if (newValue instanceof List || newValue instanceof Map) {
+			Assert.state(this.currentBeanDefinition != null, "No current bean definition set");
 			this.deferredProperties.put(this.currentBeanDefinition.getBeanName() + '.' + property,
 					new DeferredProperty(this.currentBeanDefinition, property, newValue));
 			return true;
@@ -640,6 +643,7 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 				this.currentBeanDefinition = current;
 			}
 		}
+		Assert.state(this.currentBeanDefinition != null, "No current bean definition set");
 		this.currentBeanDefinition.addProperty(name, value);
 	}
 
@@ -654,6 +658,7 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 	 * </ul>
 	 */
 	@Override
+	@Nullable
 	public Object getProperty(String name) {
 		Binding binding = getBinding();
 		if (binding != null && binding.hasVariable(name)) {
@@ -727,9 +732,10 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 
 		private final String name;
 
+		@Nullable
 		public Object value;
 
-		public DeferredProperty(GroovyBeanDefinitionWrapper beanDefinition, String name, Object value) {
+		public DeferredProperty(GroovyBeanDefinitionWrapper beanDefinition, String name, @Nullable Object value) {
 			this.beanDefinition = beanDefinition;
 			this.name = name;
 			this.value = value;
@@ -762,6 +768,7 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 		}
 
 		@Override
+		@Nullable
 		public Object getProperty(String property) {
 			if (property.equals("beanName")) {
 				return getBeanName();
@@ -769,13 +776,10 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 			else if (property.equals("source")) {
 				return getSource();
 			}
-			else if (this.beanDefinition != null) {
+			else {
 				return new GroovyPropertyValue(
 						property, this.beanDefinition.getBeanDefinition().getPropertyValues().get(property));
 			}
-			else {
-				return this.metaClass.getProperty(this, property);
-			}
 		}
 
 		@Override
@@ -804,9 +808,10 @@ public class GroovyBeanDefinitionReader extends AbstractBeanDefinitionReader imp
 
 			private final String propertyName;
 
+			@Nullable
 			private final Object propertyValue;
 
-			public GroovyPropertyValue(String propertyName, Object propertyValue) {
+			public GroovyPropertyValue(String propertyName, @Nullable Object propertyValue) {
 				this.propertyName = propertyName;
 				this.propertyValue = propertyValue;
 			}

spring-beans/src/main/java/org/springframework/beans/factory/groovy/GroovyBeanDefinitionWrapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -84,7 +84,7 @@ class GroovyBeanDefinitionWrapper extends GroovyObjectSupport {
 		this(beanName, clazz, null);
 	}
 
-	GroovyBeanDefinitionWrapper(@Nullable String beanName, Class<?> clazz, @Nullable Collection<?> constructorArgs) {
+	GroovyBeanDefinitionWrapper(@Nullable String beanName, @Nullable Class<?> clazz, @Nullable Collection<?> constructorArgs) {
 		this.beanName = beanName;
 		this.clazz = clazz;
 		this.constructorArgs = constructorArgs;
@@ -130,11 +130,12 @@ class GroovyBeanDefinitionWrapper extends GroovyObjectSupport {
 	}
 
 	BeanDefinitionHolder getBeanDefinitionHolder() {
-		return new BeanDefinitionHolder(getBeanDefinition(), getBeanName());
+		Assert.state(this.beanName != null, "Bean name must be set");
+		return new BeanDefinitionHolder(getBeanDefinition(), this.beanName);
 	}
 
-	void setParent(Object obj) {
+	void setParent(@Nullable Object obj) {
-		Assert.notNull(obj, "Parent bean cannot be set to a null runtime bean reference.");
+		Assert.notNull(obj, "Parent bean cannot be set to a null runtime bean reference");
 		if (obj instanceof String name) {
 			this.parentName = name;
 		}
@@ -148,7 +149,7 @@ class GroovyBeanDefinitionWrapper extends GroovyObjectSupport {
 		getBeanDefinition().setAbstract(false);
 	}
 
-	GroovyBeanDefinitionWrapper addProperty(String propertyName, Object propertyValue) {
+	GroovyBeanDefinitionWrapper addProperty(String propertyName, @Nullable Object propertyValue) {
 		if (propertyValue instanceof GroovyBeanDefinitionWrapper wrapper) {
 			propertyValue = wrapper.getBeanDefinition();
 		}
@@ -158,6 +159,7 @@ class GroovyBeanDefinitionWrapper extends GroovyObjectSupport {
 
 
 	@Override
+	@Nullable
 	public Object getProperty(String property) {
 		Assert.state(this.definitionWrapper != null, "BeanDefinition wrapper not initialized");
 		if (this.definitionWrapper.isReadableProperty(property)) {
@@ -170,7 +172,7 @@ class GroovyBeanDefinitionWrapper extends GroovyObjectSupport {
 	}
 
 	@Override
-	public void setProperty(String property, Object newValue) {
+	public void setProperty(String property, @Nullable Object newValue) {
 		if (PARENT.equals(property)) {
 			setParent(newValue);
 		}

spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -638,7 +638,7 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 		}
 	}
 
-	private static boolean hasAnyExternallyManagedMethod(Set<String> candidates, String methodName) {
+	private static boolean hasAnyExternallyManagedMethod(@Nullable Set<String> candidates, String methodName) {
 		if (candidates != null) {
 			for (String candidate : candidates) {
 				int indexOfDot = candidate.lastIndexOf('.');

spring-beans/src/main/java/org/springframework/beans/factory/xml/DefaultBeanDefinitionDocumentReader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -126,9 +126,10 @@ public class DefaultBeanDefinitionDocumentReader implements BeanDefinitionDocume
 		// then ultimately reset this.delegate back to its original (parent) reference.
 		// this behavior emulates a stack of delegates without actually necessitating one.
 		BeanDefinitionParserDelegate parent = this.delegate;
-		this.delegate = createDelegate(getReaderContext(), root, parent);
+		BeanDefinitionParserDelegate current = createDelegate(getReaderContext(), root, parent);
+		this.delegate = current;
 
-		if (this.delegate.isDefaultNamespace(root)) {
+		if (current.isDefaultNamespace(root)) {
 			String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
 			if (StringUtils.hasText(profileSpec)) {
 				String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
@@ -146,7 +147,7 @@ public class DefaultBeanDefinitionDocumentReader implements BeanDefinitionDocume
 		}
 
 		preProcessXml(root);
-		parseBeanDefinitions(root, this.delegate);
+		parseBeanDefinitions(root, current);
 		postProcessXml(root);
 
 		this.delegate = parent;

spring-context/src/main/java/org/springframework/cache/interceptor/CacheAspectSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -1096,7 +1096,13 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 				}
 			}
 			if (KotlinDetector.isKotlinReflectPresent() && KotlinDetector.isSuspendingFunction(method)) {
-				return Mono.fromFuture(cache.retrieve(key, () -> ((Mono<?>) invokeOperation(invoker)).toFuture()));
+				return Mono.fromFuture(cache.retrieve(key, () -> {
+					Mono<?> mono = ((Mono<?>) invokeOperation(invoker));
+					if (mono == null) {
+						mono = Mono.empty();
+					}
+					return mono.toFuture();
+				}));
 			}
 			return NOT_HANDLED;
 		}

spring-context/src/main/java/org/springframework/cache/interceptor/CacheInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -78,12 +78,13 @@ public class CacheInterceptor extends CacheAspectSupport implements MethodInterc
 		}
 	}
 
+
 	/**
 	 * Inner class to avoid a hard dependency on Kotlin at runtime.
 	 */
 	private static class KotlinDelegate {
 
-		public static Publisher<?> invokeSuspendingFunction(Method method, Object target, Object... args) {
+		public static Publisher<?> invokeSuspendingFunction(Method method, @Nullable Object target, Object... args) {
 			Continuation<?> continuation = (Continuation<?>) args[args.length - 1];
 			CoroutineContext coroutineContext = continuation.getContext().minusKey(Job.Key);
 			return CoroutinesUtils.invokeSuspendingFunction(coroutineContext, method, target, args);

spring-context/src/main/java/org/springframework/context/aot/AbstractAotProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -257,6 +257,7 @@ public abstract class AbstractAotProcessor<T> {
 			 * @return this builder for method chaining
 			 */
 			public Builder groupId(String groupId) {
+				Assert.hasText(groupId, "'groupId' must not be empty");
 				this.groupId = groupId;
 				return this;
 			}
@@ -268,6 +269,7 @@ public abstract class AbstractAotProcessor<T> {
 			 * @return this builder for method chaining
 			 */
 			public Builder artifactId(String artifactId) {
+				Assert.hasText(artifactId, "'artifactId' must not be empty");
 				this.artifactId = artifactId;
 				return this;
 			}
@@ -279,14 +281,12 @@ public abstract class AbstractAotProcessor<T> {
 				Assert.notNull(this.sourceOutput, "'sourceOutput' must not be null");
 				Assert.notNull(this.resourceOutput, "'resourceOutput' must not be null");
 				Assert.notNull(this.classOutput, "'classOutput' must not be null");
-				Assert.hasText(this.groupId, "'groupId' must not be null or empty");
+				Assert.notNull(this.groupId, "'groupId' must not be null");
-				Assert.hasText(this.artifactId, "'artifactId' must not be null or empty");
+				Assert.notNull(this.artifactId, "'artifactId' must not be null");
 				return new Settings(this.sourceOutput, this.resourceOutput, this.classOutput,
 						this.groupId, this.artifactId);
 			}
-
 		}
-
 	}
 
 }

spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -318,8 +318,8 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 		}
 	}
 
-	private void publishEvents(Object result) {
+	private void publishEvents(@Nullable Object result) {
-		if (result.getClass().isArray()) {
+		if (result != null && result.getClass().isArray()) {
 			Object[] events = ObjectUtils.toObjectArray(result);
 			for (Object event : events) {
 				publishEvent(event);

spring-context/src/main/java/org/springframework/jmx/access/MBeanProxyFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -83,18 +83,21 @@ public class MBeanProxyFactoryBean extends MBeanClientInterceptor
 	public void afterPropertiesSet() throws MBeanServerNotFoundException, MBeanInfoRetrievalException {
 		super.afterPropertiesSet();
 
+		Class<?> interfaceToUse;
 		if (this.proxyInterface == null) {
-			this.proxyInterface = getManagementInterface();
+			interfaceToUse = getManagementInterface();
-			if (this.proxyInterface == null) {
+			if (interfaceToUse == null) {
 				throw new IllegalArgumentException("Property 'proxyInterface' or 'managementInterface' is required");
 			}
+			this.proxyInterface = interfaceToUse;
 		}
 		else {
+			interfaceToUse = this.proxyInterface;
 			if (getManagementInterface() == null) {
-				setManagementInterface(this.proxyInterface);
+				setManagementInterface(interfaceToUse);
 			}
 		}
-		this.mbeanProxy = new ProxyFactory(this.proxyInterface, this).getProxy(this.beanClassLoader);
+		this.mbeanProxy = new ProxyFactory(interfaceToUse, this).getProxy(this.beanClassLoader);
 	}
 
 

spring-context/src/main/java/org/springframework/validation/DataBinder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -1035,7 +1035,7 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 			Class<?> constructorClass, String nestedPath, String name, @Nullable Object value) {
 
 		Object[] hints = null;
-		if (this.targetType.getSource() instanceof MethodParameter parameter) {
+		if (this.targetType != null && this.targetType.getSource() instanceof MethodParameter parameter) {
 			for (Annotation ann : parameter.getParameterAnnotations()) {
 				hints = ValidationAnnotationUtils.determineValidationHints(ann);
 				if (hints != null) {

spring-context/src/main/java/org/springframework/validation/beanvalidation/MethodValidationInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -79,8 +79,8 @@ import org.springframework.validation.method.ParameterValidationResult;
  */
 public class MethodValidationInterceptor implements MethodInterceptor {
 
-	private static final boolean REACTOR_PRESENT =
+	private static final boolean reactorPresent = ClassUtils.isPresent(
-			ClassUtils.isPresent("reactor.core.publisher.Mono", MethodValidationInterceptor.class.getClassLoader());
+			"reactor.core.publisher.Mono", MethodValidationInterceptor.class.getClassLoader());
 
 
 	private final MethodValidationAdapter validationAdapter;
@@ -153,7 +153,7 @@ public class MethodValidationInterceptor implements MethodInterceptor {
 		Object[] arguments = invocation.getArguments();
 		Class<?>[] groups = determineValidationGroups(invocation);
 
-		if (REACTOR_PRESENT) {
+		if (reactorPresent) {
 			arguments = ReactorValidationHelper.insertAsyncValidation(
 					this.validationAdapter.getSpringValidatorAdapter(), this.adaptViolations,
 					target, method, arguments);

spring-core/src/main/java/org/springframework/aot/generate/DefaultMethodReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -53,7 +53,7 @@ public class DefaultMethodReference implements MethodReference {
 	public CodeBlock toCodeBlock() {
 		String methodName = this.method.name;
 		if (isStatic()) {
-			Assert.state(this.declaringClass != null, "static method reference must define a declaring class");
+			Assert.state(this.declaringClass != null, "Static method reference must define a declaring class");
 			return CodeBlock.of("$T::$L", this.declaringClass, methodName);
 		}
 		else {
@@ -64,11 +64,12 @@ public class DefaultMethodReference implements MethodReference {
 	@Override
 	public CodeBlock toInvokeCodeBlock(ArgumentCodeGenerator argumentCodeGenerator,
 			@Nullable ClassName targetClassName) {
+
 		String methodName = this.method.name;
 		CodeBlock.Builder code = CodeBlock.builder();
 		if (isStatic()) {
-			Assert.state(this.declaringClass != null, "static method reference must define a declaring class");
+			Assert.state(this.declaringClass != null, "Static method reference must define a declaring class");
-			if (isSameDeclaringClass(targetClassName)) {
+			if (this.declaringClass.equals(targetClassName)) {
 				code.add("$L", methodName);
 			}
 			else {
@@ -76,7 +77,7 @@ public class DefaultMethodReference implements MethodReference {
 			}
 		}
 		else {
-			if (!isSameDeclaringClass(targetClassName)) {
+			if (this.declaringClass != null && !this.declaringClass.equals(targetClassName)) {
 				code.add(instantiateDeclaringClass(this.declaringClass));
 			}
 			code.add("$L", methodName);
@@ -117,10 +118,6 @@ public class DefaultMethodReference implements MethodReference {
 		return this.method.modifiers.contains(Modifier.STATIC);
 	}
 
-	private boolean isSameDeclaringClass(ClassName declaringClass) {
-		return this.declaringClass == null || this.declaringClass.equals(declaringClass);
-	}
-
 	@Override
 	public String toString() {
 		String methodName = this.method.name;
@@ -128,7 +125,7 @@ public class DefaultMethodReference implements MethodReference {
 			return this.declaringClass + "::" + methodName;
 		}
 		else {
-			return ((this.declaringClass != null) ?
+			return (this.declaringClass != null ?
 					"<" + this.declaringClass + ">" : "<instance>") + "::" + methodName;
 		}
 	}

spring-core/src/main/java/org/springframework/aot/hint/predicate/ReflectionHintsPredicates.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -194,6 +194,7 @@ public class ReflectionHintsPredicates {
 		return new FieldHintPredicate(field);
 	}
 
+
 	public static class TypeHintPredicate implements Predicate<RuntimeHints> {
 
 		private final TypeReference type;
@@ -212,7 +213,6 @@ public class ReflectionHintsPredicates {
 			return getTypeHint(hints) != null;
 		}
 
-
 		/**
 		 * Refine the current predicate to only match if the given {@link MemberCategory} is present.
 		 * @param memberCategory the member category
@@ -220,7 +220,10 @@ public class ReflectionHintsPredicates {
 		 */
 		public Predicate<RuntimeHints> withMemberCategory(MemberCategory memberCategory) {
 			Assert.notNull(memberCategory, "'memberCategory' must not be null");
-			return this.and(hints -> getTypeHint(hints).getMemberCategories().contains(memberCategory));
+			return and(hints -> {
+				TypeHint hint = getTypeHint(hints);
+				return (hint != null && hint.getMemberCategories().contains(memberCategory));
+			});
 		}
 
 		/**
@@ -230,7 +233,10 @@ public class ReflectionHintsPredicates {
 		 */
 		public Predicate<RuntimeHints> withMemberCategories(MemberCategory... memberCategories) {
 			Assert.notEmpty(memberCategories, "'memberCategories' must not be empty");
-			return this.and(hints -> getTypeHint(hints).getMemberCategories().containsAll(Arrays.asList(memberCategories)));
+			return and(hints -> {
+				TypeHint hint = getTypeHint(hints);
+				return (hint != null && hint.getMemberCategories().containsAll(Arrays.asList(memberCategories)));
+			});
 		}
 
 		/**
@@ -240,11 +246,14 @@ public class ReflectionHintsPredicates {
 		 */
 		public Predicate<RuntimeHints> withAnyMemberCategory(MemberCategory... memberCategories) {
 			Assert.notEmpty(memberCategories, "'memberCategories' must not be empty");
-			return this.and(hints -> Arrays.stream(memberCategories)
+			return and(hints -> {
-					.anyMatch(memberCategory -> getTypeHint(hints).getMemberCategories().contains(memberCategory)));
+				TypeHint hint = getTypeHint(hints);
+				return (hint != null && Arrays.stream(memberCategories)
+						.anyMatch(memberCategory -> hint.getMemberCategories().contains(memberCategory)));
+			});
+		}
 	}
 
-	}
 
 	public abstract static class ExecutableHintPredicate<T extends Executable> implements Predicate<RuntimeHints> {
 
@@ -289,6 +298,7 @@ public class ReflectionHintsPredicates {
 		}
 	}
 
+
 	public static class ConstructorHintPredicate extends ExecutableHintPredicate<Constructor<?>> {
 
 		ConstructorHintPredicate(Constructor<?> constructor) {
@@ -322,14 +332,16 @@ public class ReflectionHintsPredicates {
 
 		@Override
 		Predicate<RuntimeHints> exactMatch() {
-			return hints -> (hints.reflection().getTypeHint(this.executable.getDeclaringClass()) != null) &&
+			return hints -> {
-					hints.reflection().getTypeHint(this.executable.getDeclaringClass()).constructors().anyMatch(executableHint -> {
+				TypeHint hint = hints.reflection().getTypeHint(this.executable.getDeclaringClass());
+				return (hint != null && hint.constructors().anyMatch(executableHint -> {
 					List<TypeReference> parameters = TypeReference.listOf(this.executable.getParameterTypes());
 					return includes(executableHint, "<init>", parameters, this.executableMode);
-					});
+				}));
+			};
+		}
 	}
 
-	}
 
 	public static class MethodHintPredicate extends ExecutableHintPredicate<Method> {
 
@@ -367,14 +379,16 @@ public class ReflectionHintsPredicates {
 
 		@Override
 		Predicate<RuntimeHints> exactMatch() {
-			return hints -> (hints.reflection().getTypeHint(this.executable.getDeclaringClass()) != null) &&
+			return hints -> {
-					hints.reflection().getTypeHint(this.executable.getDeclaringClass()).methods().anyMatch(executableHint -> {
+				TypeHint hint = hints.reflection().getTypeHint(this.executable.getDeclaringClass());
+				return (hint != null && hint.methods().anyMatch(executableHint -> {
 					List<TypeReference> parameters = TypeReference.listOf(this.executable.getParameterTypes());
 					return includes(executableHint, this.executable.getName(), parameters, this.executableMode);
-					});
+				}));
+			};
+		}
 	}
 
-	}
 
 	public static class FieldHintPredicate implements Predicate<RuntimeHints> {
 
@@ -406,7 +420,6 @@ public class ReflectionHintsPredicates {
 			return typeHint.fields().anyMatch(fieldHint ->
 					this.field.getName().equals(fieldHint.getName()));
 		}
-
 	}
 
 }

spring-core/src/main/java/org/springframework/core/CoroutinesUtils.java

@@ -46,6 +46,7 @@ import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
@@ -64,6 +65,7 @@ public abstract class CoroutinesUtils {
 
 	private static final KType publisherType = KClassifiers.getStarProjectedType(JvmClassMappingKt.getKotlinClass(Publisher.class));
 
+
 	/**
 	 * Convert a {@link Deferred} instance to a {@link Mono}.
 	 */
@@ -109,9 +111,10 @@ public abstract class CoroutinesUtils {
 	 * @since 6.0
 	 */
 	@SuppressWarnings({"deprecation", "DataFlowIssue"})
-	public static Publisher<?> invokeSuspendingFunction(CoroutineContext context, Method method, Object target,
+	public static Publisher<?> invokeSuspendingFunction(
-			Object... args) {
+			CoroutineContext context, Method method, @Nullable Object target, Object... args) {
-		Assert.isTrue(KotlinDetector.isSuspendingFunction(method), "'method' must be a suspending function");
+
+		Assert.isTrue(KotlinDetector.isSuspendingFunction(method), "Method must be a suspending function");
 		KFunction<?> function = Objects.requireNonNull(ReflectJvmMapping.getKotlinFunction(method));
 		if (method.isAccessible() && !KCallablesJvm.isAccessible(function)) {
 			KCallablesJvm.setAccessible(function, true);

spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java

@@ -650,11 +650,10 @@ public abstract class AnnotationUtils {
 			return null;
 		}
 
-		return (Class<?>) MergedAnnotations.from(clazz, SearchStrategy.SUPERCLASS)
+		MergedAnnotation<?> merged = MergedAnnotations.from(clazz, SearchStrategy.SUPERCLASS).stream()
-				.stream()
 				.filter(MergedAnnotationPredicates.typeIn(annotationTypes).and(MergedAnnotation::isDirectlyPresent))
-				.map(MergedAnnotation::getSource)
 				.findFirst().orElse(null);
+		return (merged != null && merged.getSource() instanceof Class<?> sourceClass ? sourceClass : null);
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/annotation/MergedAnnotationsCollection.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -167,6 +167,7 @@ final class MergedAnnotationsCollection implements MergedAnnotations {
 		MergedAnnotation<A> result = null;
 		for (int i = 0; i < this.annotations.length; i++) {
 			MergedAnnotation<?> root = this.annotations[i];
+			if (root != null) {
 				AnnotationTypeMappings mappings = this.mappings[i];
 				for (int mappingIndex = 0; mappingIndex < mappings.size(); mappingIndex++) {
 					AnnotationTypeMapping mapping = mappings.get(mappingIndex);
@@ -183,6 +184,7 @@ final class MergedAnnotationsCollection implements MergedAnnotations {
 					}
 				}
 			}
+		}
 		return result;
 	}
 

spring-core/src/main/java/org/springframework/core/convert/support/StringToRegexConverter.java

@@ -28,7 +28,7 @@ import org.springframework.lang.Nullable;
  * @author Sebastien Deleuze
  * @since 6.1
  */
-class StringToRegexConverter implements Converter<String, Regex> {
+final class StringToRegexConverter implements Converter<String, Regex> {
 
 	@Override
 	@Nullable

spring-core/src/main/java/org/springframework/core/io/buffer/DataBufferUtils.java

@@ -1113,13 +1113,13 @@ public abstract class DataBufferUtils {
 		}
 
 		@Override
-		public void failed(Throwable exc, Attachment attachment) {
+		public void failed(Throwable ex, Attachment attachment) {
 			attachment.iterator().close();
 			release(attachment.dataBuffer());
 
 			closeChannel(this.channel);
 			this.state.set(State.DISPOSED);
-			this.sink.error(exc);
+			this.sink.error(ex);
 		}
 
 		private enum State {
@@ -1178,7 +1178,6 @@ public abstract class DataBufferUtils {
 		public Context currentContext() {
 			return Context.of(this.sink.contextView());
 		}
-
 	}
 
 
@@ -1273,13 +1272,13 @@ public abstract class DataBufferUtils {
 		}
 
 		@Override
-		public void failed(Throwable exc, Attachment attachment) {
+		public void failed(Throwable ex, Attachment attachment) {
 			attachment.iterator().close();
 
 			this.sink.next(attachment.dataBuffer());
 			this.writing.set(false);
 
-			this.sink.error(exc);
+			this.sink.error(ex);
 		}
 
 		@Override
@@ -1288,9 +1287,6 @@ public abstract class DataBufferUtils {
 		}
 
 		private record Attachment(ByteBuffer byteBuffer, DataBuffer dataBuffer, DataBuffer.ByteBufferIterator iterator) {}
-
-
 	}
 
-
 }

spring-core/src/main/java/org/springframework/core/io/buffer/OutputStreamPublisher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -178,13 +178,14 @@ final class OutputStreamPublisher implements Publisher<DataBuffer> {
 				if (isCancelled(previousState)) {
 					return;
 				}
-
 				if (isTerminated(previousState)) {
 					// failure due to illegal requestN
-					this.actual.onError(this.error);
+					Throwable error = this.error;
+					if (error != null) {
+						this.actual.onError(error);
 						return;
 					}
-
+				}
 				this.actual.onError(ex);
 				return;
 			}
@@ -193,13 +194,14 @@ final class OutputStreamPublisher implements Publisher<DataBuffer> {
 			if (isCancelled(previousState)) {
 				return;
 			}
-
 			if (isTerminated(previousState)) {
 				// failure due to illegal requestN
-				this.actual.onError(this.error);
+				Throwable error = this.error;
+				if (error != null) {
+					this.actual.onError(error);
 					return;
 				}
-
+			}
 			this.actual.onComplete();
 		}
 
@@ -209,16 +211,13 @@ final class OutputStreamPublisher implements Publisher<DataBuffer> {
 			if (n <= 0) {
 				this.error = new IllegalArgumentException("request should be a positive number");
 				long previousState = tryTerminate();
-
 				if (isTerminated(previousState) || isCancelled(previousState)) {
 					return;
 				}
-
 				if (previousState > 0) {
 					// error should eventually be observed and propagated
 					return;
 				}
-
 				// resume parked thread, so it can observe error and propagate it
 				resume();
 				return;
@@ -276,11 +275,9 @@ final class OutputStreamPublisher implements Publisher<DataBuffer> {
 		private long tryCancel() {
 			while (true) {
 				long r = this.requested.get();
-
 				if (isCancelled(r)) {
 					return r;
 				}
-
 				if (this.requested.compareAndSet(r, Long.MIN_VALUE)) {
 					return r;
 				}
@@ -290,11 +287,9 @@ final class OutputStreamPublisher implements Publisher<DataBuffer> {
 		private long tryTerminate() {
 			while (true) {
 				long r = this.requested.get();
-
 				if (isCancelled(r) || isTerminated(r)) {
 					return r;
 				}
-
 				if (this.requested.compareAndSet(r, Long.MIN_VALUE | Long.MAX_VALUE)) {
 					return r;
 				}

spring-core/src/main/java/org/springframework/util/ClassUtils.java

@@ -557,7 +557,7 @@ public abstract class ClassUtils {
 	 * @see Void
 	 * @see Void#TYPE
 	 */
-	public static boolean isVoidType(Class<?> type) {
+	public static boolean isVoidType(@Nullable Class<?> type) {
 		return (type == void.class || type == Void.class);
 	}
 

spring-core/src/main/java/org/springframework/util/SerializationUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -99,7 +99,9 @@ public abstract class SerializationUtils {
 	 */
 	@SuppressWarnings("unchecked")
 	public static <T extends Serializable> T clone(T object) {
-		return (T) SerializationUtils.deserialize(SerializationUtils.serialize(object));
+		Object result = SerializationUtils.deserialize(SerializationUtils.serialize(object));
+		Assert.state(result != null, "Deserialized object must not be null");
+		return (T) result;
 	}
 
 }

spring-core/src/test/java/org/springframework/aot/generate/DefaultMethodReferenceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -88,7 +88,7 @@ class DefaultMethodReferenceTests {
 		MethodSpec method = createTestMethod("methodName", new TypeName[0], Modifier.STATIC);
 		MethodReference methodReference = new DefaultMethodReference(method, null);
 		assertThatIllegalStateException().isThrownBy(methodReference::toCodeBlock)
-				.withMessage("static method reference must define a declaring class");
+				.withMessage("Static method reference must define a declaring class");
 	}
 
 	@Test

spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -230,7 +230,7 @@ public class ConstructorReference extends SpelNodeImpl {
 				InlineList initializer = (InlineList) getChild(1);
 				sb.append("[] ").append(initializer.toStringAST());
 			}
-			else {
+			else if (this.dimensions != null) {
 				// new int[3], new java.lang.String[3][4], etc.
 				for (SpelNodeImpl dimension : this.dimensions) {
 					sb.append('[').append(dimension.toStringAST()).append(']');

spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java

@@ -222,7 +222,9 @@ public class Indexer extends SpelNodeImpl {
 		}
 
 		if (this.indexedType == IndexedType.ARRAY) {
-			int insn = switch (this.exitTypeDescriptor) {
+			String exitTypeDescriptor = this.exitTypeDescriptor;
+			Assert.state(exitTypeDescriptor != null, "Array not compilable without descriptor");
+			int insn = switch (exitTypeDescriptor) {
 				case "D" -> {
 					mv.visitTypeInsn(CHECKCAST, "[D");
 					yield DALOAD;
@@ -258,8 +260,8 @@ public class Indexer extends SpelNodeImpl {
 					yield CALOAD;
 				}
 				default -> {
-					mv.visitTypeInsn(CHECKCAST, "["+ this.exitTypeDescriptor +
+					mv.visitTypeInsn(CHECKCAST, "["+ exitTypeDescriptor +
-							(CodeFlow.isPrimitiveArray(this.exitTypeDescriptor) ? "" : ";"));
+							(CodeFlow.isPrimitiveArray(exitTypeDescriptor) ? "" : ";"));
 					yield AALOAD;
 				}
 			};

spring-expression/src/main/java/org/springframework/expression/spel/standard/Token.java

@@ -55,7 +55,7 @@ class Token {
 	 * @param startPos the exact start position
 	 * @param endPos the index of the last character
 	 */
-	Token(TokenKind tokenKind, char[] tokenData, int startPos, int endPos) {
+	Token(TokenKind tokenKind, @Nullable char[] tokenData, int startPos, int endPos) {
 		this.kind = tokenKind;
 		this.data = (tokenData != null ? new String(tokenData) : null);
 		this.startPos = startPos;

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java

@@ -296,7 +296,8 @@ public abstract class ReflectionHelper {
 				TypeDescriptor sourceType = TypeDescriptor.forObject(argument);
 				if (argument == null) {
 					// Perform the equivalent of GenericConversionService.convertNullSource() for a single argument.
-					if (targetType.getElementTypeDescriptor().getObjectType() == Optional.class) {
+					TypeDescriptor elementDesc = targetType.getElementTypeDescriptor();
+					if (elementDesc != null && elementDesc.getObjectType() == Optional.class) {
 						arguments[varargsPosition] = Optional.empty();
 						conversionOccurred = true;
 					}
@@ -383,7 +384,8 @@ public abstract class ReflectionHelper {
 				TypeDescriptor sourceType = TypeDescriptor.forObject(argument);
 				if (argument == null) {
 					// Perform the equivalent of GenericConversionService.convertNullSource() for a single argument.
-					if (varArgContentType.getElementTypeDescriptor().getObjectType() == Optional.class) {
+					TypeDescriptor elementDesc = varArgContentType.getElementTypeDescriptor();
+					if (elementDesc != null && elementDesc.getObjectType() == Optional.class) {
 						arguments[varargsPosition] = Optional.empty();
 						conversionOccurred = true;
 					}
@@ -408,7 +410,6 @@ public abstract class ReflectionHelper {
 			}
 			// Otherwise, convert remaining arguments to the varargs element type.
 			else {
-				Assert.state(varArgContentType != null, "No element type");
 				for (int i = varargsPosition; i < arguments.length; i++) {
 					Object argument = arguments[i];
 					arguments[i] = converter.convertValue(argument, TypeDescriptor.forObject(argument), varArgContentType);

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/CallMetaDataProviderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -88,6 +88,10 @@ public final class CallMetaDataProviderFactory {
 		try {
 			return JdbcUtils.extractDatabaseMetaData(dataSource, databaseMetaData -> {
 				String databaseProductName = JdbcUtils.commonDatabaseName(databaseMetaData.getDatabaseProductName());
+				if (databaseProductName == null) {
+					databaseProductName = "";
+				}
+
 				boolean accessProcedureColumnMetaData = context.isAccessCallParameterMetaData();
 				if (context.isFunction()) {
 					if (!supportedDatabaseProductsForFunctions.contains(databaseProductName)) {

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/TableMetaDataContext.java

@@ -438,7 +438,7 @@ public class TableMetaDataContext {
 			this.quoting = StringUtils.hasText(identifierQuoteString);
 		}
 
-		public void appendTo(StringBuilder stringBuilder, String item) {
+		public void appendTo(StringBuilder stringBuilder, @Nullable String item) {
 			if (this.quoting) {
 				stringBuilder.append(this.identifierQuoteString)
 						.append(item).append(this.identifierQuoteString);

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/embedded/EmbeddedDatabaseFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -84,8 +84,9 @@ public class EmbeddedDatabaseFactoryBean extends EmbeddedDatabaseFactory
 
 	@Override
 	public void destroy() {
-		if (this.databaseCleaner != null && getDataSource() != null) {
+		DatabasePopulator cleaner = this.databaseCleaner;
-			DatabasePopulatorUtils.execute(this.databaseCleaner, getDataSource());
+		if (cleaner != null && getDataSource() != null) {
+			DatabasePopulatorUtils.execute(cleaner, getDataSource());
 		}
 		shutdownDatabase();
 	}

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/ChannelSendOperator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -309,9 +309,10 @@ class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		}
 
 		private boolean emitCachedSignals() {
-			if (this.error != null) {
+			Throwable error = this.error;
+			if (error != null) {
 				try {
-					requiredWriteSubscriber().onError(this.error);
+					requiredWriteSubscriber().onError(error);
 				}
 				finally {
 					releaseCachedItem();

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/InvocableHandlerMethod.java

@@ -33,7 +33,6 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.core.ReactiveAdapter;
 import org.springframework.core.ReactiveAdapterRegistry;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.HandlerMethod;
 import org.springframework.messaging.handler.invocation.MethodArgumentResolutionException;
@@ -153,7 +152,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 			MethodParameter returnType = getReturnType();
 			Class<?> reactiveType = (isSuspendingFunction ? value.getClass() : returnType.getParameterType());
 			ReactiveAdapter adapter = this.reactiveAdapterRegistry.getAdapter(reactiveType);
-			return (isAsyncVoidReturnType(returnType, adapter) ?
+			return (adapter != null && isAsyncVoidReturnType(returnType, adapter) ?
 					Mono.from(adapter.toPublisher(value)) : Mono.justOrEmpty(value));
 		});
 	}
@@ -200,8 +199,8 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		}
 	}
 
-	private boolean isAsyncVoidReturnType(MethodParameter returnType, @Nullable ReactiveAdapter reactiveAdapter) {
+	private boolean isAsyncVoidReturnType(MethodParameter returnType, ReactiveAdapter reactiveAdapter) {
-		if (reactiveAdapter != null && reactiveAdapter.supportsEmpty()) {
+		if (reactiveAdapter.supportsEmpty()) {
 			if (reactiveAdapter.isNoValue()) {
 				return true;
 			}

spring-orm/src/main/java/org/springframework/orm/hibernate5/HibernateTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -631,8 +631,9 @@ public class HibernateTransactionManager extends AbstractPlatformTransactionMana
 			TransactionSynchronizationManager.unbindResource(sessionFactory);
 		}
 		TransactionSynchronizationManager.bindResource(sessionFactory, resourcesHolder.getSessionHolder());
-		if (getDataSource() != null && resourcesHolder.getConnectionHolder() != null) {
+		ConnectionHolder connectionHolder = resourcesHolder.getConnectionHolder();
-			TransactionSynchronizationManager.bindResource(getDataSource(), resourcesHolder.getConnectionHolder());
+		if (connectionHolder != null && getDataSource() != null) {
+			TransactionSynchronizationManager.bindResource(getDataSource(), connectionHolder);
 		}
 	}
 

spring-orm/src/main/java/org/springframework/orm/jpa/JpaTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -535,8 +535,9 @@ public class JpaTransactionManager extends AbstractPlatformTransactionManager
 		SuspendedResourcesHolder resourcesHolder = (SuspendedResourcesHolder) suspendedResources;
 		TransactionSynchronizationManager.bindResource(
 				obtainEntityManagerFactory(), resourcesHolder.getEntityManagerHolder());
-		if (getDataSource() != null && resourcesHolder.getConnectionHolder() != null) {
+		ConnectionHolder connectionHolder = resourcesHolder.getConnectionHolder();
-			TransactionSynchronizationManager.bindResource(getDataSource(), resourcesHolder.getConnectionHolder());
+		if (connectionHolder != null && getDataSource() != null) {
+			TransactionSynchronizationManager.bindResource(getDataSource(), connectionHolder);
 		}
 	}
 

spring-test/src/main/java/org/springframework/test/context/aot/GeneratedMapUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -42,14 +42,14 @@ final class GeneratedMapUtils {
 	 * @param methodName the name of the static method to invoke
 	 * @return an unmodifiable map retrieved from a static method
 	 */
-	@SuppressWarnings({ "rawtypes", "unchecked" })
+	@SuppressWarnings({"rawtypes", "unchecked"})
 	static Map loadMap(String className, String methodName) {
 		try {
 			Class<?> clazz = ClassUtils.forName(className, null);
 			Method method = ReflectionUtils.findMethod(clazz, methodName);
 			Assert.state(method != null, () -> "No %s() method found in %s".formatted(methodName, className));
 			Map map = (Map) ReflectionUtils.invokeMethod(method, null);
-			return Collections.unmodifiableMap(map);
+			return (map != null ? Collections.unmodifiableMap(map) : Collections.emptyMap());
 		}
 		catch (IllegalStateException ex) {
 			throw ex;

spring-test/src/main/java/org/springframework/test/context/aot/TestContextGenerationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -20,6 +20,7 @@ import org.springframework.aot.generate.ClassNameGenerator;
 import org.springframework.aot.generate.DefaultGenerationContext;
 import org.springframework.aot.generate.GeneratedFiles;
 import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.lang.Nullable;
 
 /**
  * Extension of {@link DefaultGenerationContext} with a custom implementation of
@@ -30,6 +31,7 @@ import org.springframework.aot.hint.RuntimeHints;
  */
 class TestContextGenerationContext extends DefaultGenerationContext {
 
+	@Nullable
 	private final String featureName;
 
 
@@ -41,8 +43,9 @@ class TestContextGenerationContext extends DefaultGenerationContext {
 	 * @param generatedFiles the generated files
 	 * @param runtimeHints the runtime hints
 	 */
-	TestContextGenerationContext(ClassNameGenerator classNameGenerator, GeneratedFiles generatedFiles,
+	TestContextGenerationContext(
-			RuntimeHints runtimeHints) {
+			ClassNameGenerator classNameGenerator, GeneratedFiles generatedFiles, RuntimeHints runtimeHints) {
+
 		super(classNameGenerator, generatedFiles, runtimeHints);
 		this.featureName = null;
 	}

spring-test/src/main/java/org/springframework/test/context/observation/MicrometerObservationRegistryTestExecutionListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -25,6 +25,7 @@ import org.apache.commons.logging.LogFactory;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.core.Conventions;
+import org.springframework.lang.Nullable;
 import org.springframework.test.context.TestContext;
 import org.springframework.test.context.support.AbstractTestExecutionListener;
 import org.springframework.util.ReflectionUtils;
@@ -67,6 +68,7 @@ class MicrometerObservationRegistryTestExecutionListener extends AbstractTestExe
 	static final String OBSERVATION_THREAD_LOCAL_ACCESSOR_CLASS_NAME =
 			"io.micrometer.observation.contextpropagation.ObservationThreadLocalAccessor";
 
+	@Nullable
 	private static final String ERROR_MESSAGE;
 
 	static {

spring-test/src/main/java/org/springframework/test/context/support/TestPropertySourceAttributes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -143,7 +143,7 @@ class TestPropertySourceAttributes {
 	}
 
 	private void addPropertiesAndLocations(List<PropertySourceDescriptor> descriptors, String[] properties,
-			Class<?> declaringClass, String encoding, boolean prepend) {
+			Class<?> declaringClass, @Nullable String encoding, boolean prepend) {
 
 		if (hasNoLocations(descriptors) && ObjectUtils.isEmpty(properties)) {
 			String defaultPropertiesFile = detectDefaultPropertiesFile(declaringClass);

spring-web/src/main/java/org/springframework/http/client/observation/DefaultClientRequestObservationConvention.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -24,9 +24,11 @@ import io.micrometer.common.KeyValues;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
+import org.springframework.http.client.ClientHttpRequest;
 import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.http.client.observation.ClientHttpObservationDocumentation.HighCardinalityKeyNames;
 import org.springframework.http.client.observation.ClientHttpObservationDocumentation.LowCardinalityKeyNames;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -84,8 +86,10 @@ public class DefaultClientRequestObservationConvention implements ClientRequestO
 	}
 
 	@Override
+	@Nullable
 	public String getContextualName(ClientRequestObservationContext context) {
-		return "http " + context.getCarrier().getMethod().name().toLowerCase();
+		ClientHttpRequest request = context.getCarrier();
+		return (request != null ? "http " + request.getMethod().name().toLowerCase() : null);
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/http/client/reactive/ReactorNetty2ClientHttpResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -126,9 +126,9 @@ class ReactorNetty2ClientHttpResponse implements ClientHttpResponse {
 				.flatMap(Collection::stream)
 				.forEach(cookie -> result.add(cookie.name().toString(),
 						ResponseCookie.fromClientResponse(cookie.name().toString(), cookie.value().toString())
-								.domain(cookie.domain() != null ? cookie.domain().toString() : null)
+								.domain(toString(cookie.domain()))
-								.path(cookie.path() != null ? cookie.path().toString() : null)
+								.path(toString(cookie.path()))
-								.maxAge(cookie.maxAge() != null ? cookie.maxAge() : -1L)
+								.maxAge(toLong(cookie.maxAge()))
 								.secure(cookie.isSecure())
 								.httpOnly(cookie.isHttpOnly())
 								.sameSite(getSameSite(cookie))
@@ -136,6 +136,15 @@ class ReactorNetty2ClientHttpResponse implements ClientHttpResponse {
 		return CollectionUtils.unmodifiableMultiValueMap(result);
 	}
 
+	@Nullable
+	private static String toString(@Nullable CharSequence value) {
+		return (value != null ? value.toString() : null);
+	}
+
+	private static long toLong(@Nullable Long value) {
+		return (value != null ? value : -1);
+	}
+
 	@Nullable
 	private static String getSameSite(HttpSetCookie cookie) {
 		if (cookie instanceof DefaultHttpSetCookie defaultCookie && defaultCookie.sameSite() != null) {

spring-web/src/main/java/org/springframework/http/server/reactive/ChannelSendOperator.java

@@ -301,9 +301,10 @@ public class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		}
 
 		private boolean emitCachedSignals() {
-			if (this.error != null) {
+			Throwable error = this.error;
+			if (error != null) {
 				try {
-					requiredWriteSubscriber().onError(this.error);
+					requiredWriteSubscriber().onError(error);
 				}
 				finally {
 					releaseCachedItem();

spring-web/src/main/java/org/springframework/web/context/request/ServletWebRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -205,32 +205,32 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 	}
 
 	@Override
-	public boolean checkNotModified(@Nullable String eTag, long lastModifiedTimestamp) {
+	public boolean checkNotModified(@Nullable String etag, long lastModifiedTimestamp) {
 		HttpServletResponse response = getResponse();
 		if (this.notModified || (response != null && HttpStatus.OK.value() != response.getStatus())) {
 			return this.notModified;
 		}
 		// Evaluate conditions in order of precedence.
 		// See https://datatracker.ietf.org/doc/html/rfc9110#section-13.2.2
-		if (validateIfMatch(eTag)) {
+		if (validateIfMatch(etag)) {
-			updateResponseStateChanging(eTag, lastModifiedTimestamp);
+			updateResponseStateChanging(etag, lastModifiedTimestamp);
 			return this.notModified;
 		}
 		// 2) If-Unmodified-Since
 		else if (validateIfUnmodifiedSince(lastModifiedTimestamp)) {
-			updateResponseStateChanging(eTag, lastModifiedTimestamp);
+			updateResponseStateChanging(etag, lastModifiedTimestamp);
 			return this.notModified;
 		}
 		// 3) If-None-Match
-		if (!validateIfNoneMatch(eTag)) {
+		if (!validateIfNoneMatch(etag)) {
 			// 4) If-Modified-Since
 			validateIfModifiedSince(lastModifiedTimestamp);
 		}
-		updateResponseIdempotent(eTag, lastModifiedTimestamp);
+		updateResponseIdempotent(etag, lastModifiedTimestamp);
 		return this.notModified;
 	}
 
-	private boolean validateIfMatch(@Nullable String eTag) {
+	private boolean validateIfMatch(@Nullable String etag) {
 		if (SAFE_METHODS.contains(getRequest().getMethod())) {
 			return false;
 		}
@@ -238,37 +238,37 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		if (!ifMatchHeaders.hasMoreElements()) {
 			return false;
 		}
-		this.notModified = matchRequestedETags(ifMatchHeaders, eTag, false);
+		this.notModified = matchRequestedETags(ifMatchHeaders, etag, false);
 		return true;
 	}
 
-	private boolean validateIfNoneMatch(@Nullable String eTag) {
+	private boolean validateIfNoneMatch(@Nullable String etag) {
 		Enumeration<String> ifNoneMatchHeaders = getRequest().getHeaders(HttpHeaders.IF_NONE_MATCH);
 		if (!ifNoneMatchHeaders.hasMoreElements()) {
 			return false;
 		}
-		this.notModified = !matchRequestedETags(ifNoneMatchHeaders, eTag, true);
+		this.notModified = !matchRequestedETags(ifNoneMatchHeaders, etag, true);
 		return true;
 	}
 
-	private boolean matchRequestedETags(Enumeration<String> requestedETags, @Nullable String eTag, boolean weakCompare) {
+	private boolean matchRequestedETags(Enumeration<String> requestedETags, @Nullable String etag, boolean weakCompare) {
-		eTag = padEtagIfNecessary(eTag);
+		etag = padEtagIfNecessary(etag);
 		while (requestedETags.hasMoreElements()) {
 			// Compare weak/strong ETags as per https://datatracker.ietf.org/doc/html/rfc9110#section-8.8.3
-			Matcher eTagMatcher = ETAG_HEADER_VALUE_PATTERN.matcher(requestedETags.nextElement());
+			Matcher etagMatcher = ETAG_HEADER_VALUE_PATTERN.matcher(requestedETags.nextElement());
-			while (eTagMatcher.find()) {
+			while (etagMatcher.find()) {
 				// only consider "lost updates" checks for unsafe HTTP methods
-				if ("*".equals(eTagMatcher.group()) && StringUtils.hasLength(eTag)
+				if ("*".equals(etagMatcher.group()) && StringUtils.hasLength(etag)
 						&& !SAFE_METHODS.contains(getRequest().getMethod())) {
 					return false;
 				}
 				if (weakCompare) {
-					if (eTagWeakMatch(eTag, eTagMatcher.group(1))) {
+					if (etagWeakMatch(etag, etagMatcher.group(1))) {
 						return false;
 					}
 				}
 				else {
-					if (eTagStrongMatch(eTag, eTagMatcher.group(1))) {
+					if (etagStrongMatch(etag, etagMatcher.group(1))) {
 						return false;
 					}
 				}
@@ -288,14 +288,14 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		return "\"" + etag + "\"";
 	}
 
-	private boolean eTagStrongMatch(@Nullable String first, @Nullable String second) {
+	private boolean etagStrongMatch(@Nullable String first, @Nullable String second) {
 		if (!StringUtils.hasLength(first) || first.startsWith("W/")) {
 			return false;
 		}
 		return first.equals(second);
 	}
 
-	private boolean eTagWeakMatch(@Nullable String first, @Nullable String second) {
+	private boolean etagWeakMatch(@Nullable String first, @Nullable String second) {
 		if (!StringUtils.hasLength(first) || !StringUtils.hasLength(second)) {
 			return false;
 		}
@@ -308,12 +308,12 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		return first.equals(second);
 	}
 
-	private void updateResponseStateChanging(@Nullable String eTag, long lastModifiedTimestamp) {
+	private void updateResponseStateChanging(@Nullable String etag, long lastModifiedTimestamp) {
 		if (this.notModified && getResponse() != null) {
 			getResponse().setStatus(HttpStatus.PRECONDITION_FAILED.value());
 		}
 		else {
-			addCachingResponseHeaders(eTag, lastModifiedTimestamp);
+			addCachingResponseHeaders(etag, lastModifiedTimestamp);
 		}
 	}
 
@@ -340,24 +340,24 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		}
 	}
 
-	private void updateResponseIdempotent(@Nullable String eTag, long lastModifiedTimestamp) {
+	private void updateResponseIdempotent(@Nullable String etag, long lastModifiedTimestamp) {
 		if (getResponse() != null) {
 			boolean isHttpGetOrHead = SAFE_METHODS.contains(getRequest().getMethod());
 			if (this.notModified) {
 				getResponse().setStatus(isHttpGetOrHead ?
 						HttpStatus.NOT_MODIFIED.value() : HttpStatus.PRECONDITION_FAILED.value());
 			}
-			addCachingResponseHeaders(eTag, lastModifiedTimestamp);
+			addCachingResponseHeaders(etag, lastModifiedTimestamp);
 		}
 	}
 
-	private void addCachingResponseHeaders(@Nullable String eTag, long lastModifiedTimestamp) {
+	private void addCachingResponseHeaders(@Nullable String etag, long lastModifiedTimestamp) {
-		if (SAFE_METHODS.contains(getRequest().getMethod())) {
+		if (getResponse() != null && SAFE_METHODS.contains(getRequest().getMethod())) {
 			if (lastModifiedTimestamp > 0 && parseDateValue(getResponse().getHeader(HttpHeaders.LAST_MODIFIED)) == -1) {
 				getResponse().setDateHeader(HttpHeaders.LAST_MODIFIED, lastModifiedTimestamp);
 			}
-			if (StringUtils.hasLength(eTag) && getResponse().getHeader(HttpHeaders.ETAG) == null) {
+			if (StringUtils.hasLength(etag) && getResponse().getHeader(HttpHeaders.ETAG) == null) {
-				getResponse().setHeader(HttpHeaders.ETAG, padEtagIfNecessary(eTag));
+				getResponse().setHeader(HttpHeaders.ETAG, padEtagIfNecessary(etag));
 			}
 		}
 	}

spring-web/src/main/java/org/springframework/web/context/request/async/CallableInterceptorChain.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -68,6 +68,7 @@ class CallableInterceptorChain {
 		}
 	}
 
+	@Nullable
 	public Object applyPostProcess(NativeWebRequest request, Callable<?> task, @Nullable Object concurrentResult) {
 		Throwable exceptionResult = null;
 		for (int i = this.preProcessIndex; i >= 0; i--) {
@@ -86,7 +87,7 @@ class CallableInterceptorChain {
 				}
 			}
 		}
-		return (exceptionResult != null) ? exceptionResult : concurrentResult;
+		return (exceptionResult != null ? exceptionResult : concurrentResult);
 	}
 
 	public Object triggerAfterTimeout(NativeWebRequest request, Callable<?> task) {

spring-web/src/main/java/org/springframework/web/context/request/async/DeferredResult.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -96,7 +96,7 @@ public class DeferredResult<T> {
 	 * timeout depends on the default of the underlying server.
 	 * @param timeoutValue timeout value in milliseconds
 	 */
-	public DeferredResult(Long timeoutValue) {
+	public DeferredResult(@Nullable Long timeoutValue) {
 		this(timeoutValue, () -> RESULT_NONE);
 	}
 
@@ -239,11 +239,11 @@ public class DeferredResult<T> {
 	 * {@code false} if the result was already set or the async request expired
 	 * @see #isSetOrExpired()
 	 */
-	public boolean setResult(T result) {
+	public boolean setResult(@Nullable T result) {
 		return setResultInternal(result);
 	}
 
-	private boolean setResultInternal(Object result) {
+	private boolean setResultInternal(@Nullable Object result) {
 		// Immediate expiration check outside of the result lock
 		if (isSetOrExpired()) {
 			return false;

spring-web/src/main/java/org/springframework/web/filter/reactive/ServerHttpObservationFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -37,7 +37,6 @@ import org.springframework.web.server.WebFilter;
 import org.springframework.web.server.WebFilterChain;
 import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
 
-
 /**
  * {@link org.springframework.web.server.WebFilter} that creates {@link Observation observations}
  * for HTTP exchanges. This collects information about the execution time and
@@ -160,6 +159,7 @@ public class ServerHttpObservationFilter implements WebFilter {
 
 		private void doOnTerminate(ServerRequestObservationContext context) {
 			ServerHttpResponse response = context.getResponse();
+			if (response != null) {
 				if (response.isCommitted()) {
 					this.observation.stop();
 				}
@@ -171,5 +171,6 @@ public class ServerHttpObservationFilter implements WebFilter {
 				}
 			}
 		}
+	}
 
 }

spring-web/src/main/java/org/springframework/web/method/annotation/AbstractNamedValueMethodArgumentResolver.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.method.annotation;
 
+import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 import java.util.Map;
 import java.util.Objects;
@@ -284,7 +285,10 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 		WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
 		Class<?> parameterType = parameter.getParameterType();
 		if (KotlinDetector.isKotlinPresent() && KotlinDetector.isInlineClass(parameterType)) {
-			parameterType = BeanUtils.findPrimaryConstructor(parameterType).getParameterTypes()[0];
+			Constructor<?> ctor = BeanUtils.findPrimaryConstructor(parameterType);
+			if (ctor != null) {
+				parameterType = ctor.getParameterTypes()[0];
+			}
 		}
 		try {
 			arg = binder.convertIfNecessary(arg, parameterType, parameter);

spring-web/src/main/java/org/springframework/web/server/adapter/HttpWebHandlerAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -414,6 +414,7 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 
 		private void doOnTerminate(ServerRequestObservationContext context) {
 			ServerHttpResponse response = context.getResponse();
+			if (response != null) {
 				if (response.isCommitted()) {
 					this.observation.stop();
 				}
@@ -425,5 +426,6 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 				}
 			}
 		}
+	}
 
 }

spring-web/src/main/java/org/springframework/web/util/pattern/RegexPathElement.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -134,7 +134,7 @@ class RegexPathElement extends PathElement {
 		if (matches) {
 			if (isNoMorePattern()) {
 				if (matchingContext.determineRemainingPath &&
-						(this.variableNames.isEmpty() || textToMatch.length() > 0)) {
+						(this.variableNames.isEmpty() || !textToMatch.isEmpty())) {
 					matchingContext.remainingPathIndex = pathIndex + 1;
 					matches = true;
 				}
@@ -142,9 +142,9 @@ class RegexPathElement extends PathElement {
 					// No more pattern, is there more data?
 					// If pattern is capturing variables there must be some actual data to bind to them
 					matches = (pathIndex + 1 >= matchingContext.pathLength) &&
-							(this.variableNames.isEmpty() || textToMatch.length() > 0);
+							(this.variableNames.isEmpty() || !textToMatch.isEmpty());
 					if (!matches && matchingContext.isMatchOptionalTrailingSeparator()) {
-						matches = (this.variableNames.isEmpty() || textToMatch.length() > 0) &&
+						matches = (this.variableNames.isEmpty() || !textToMatch.isEmpty()) &&
 								(pathIndex + 2 >= matchingContext.pathLength) &&
 								matchingContext.isSeparator(pathIndex + 1);
 					}

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultClientRequestObservationConvention.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -24,6 +24,7 @@ import io.micrometer.common.KeyValues;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 import org.springframework.web.reactive.function.client.ClientHttpObservationDocumentation.HighCardinalityKeyNames;
 import org.springframework.web.reactive.function.client.ClientHttpObservationDocumentation.LowCardinalityKeyNames;
@@ -88,8 +89,10 @@ public class DefaultClientRequestObservationConvention implements ClientRequestO
 	}
 
 	@Override
+	@Nullable
 	public String getContextualName(ClientRequestObservationContext context) {
-		return "http " + context.getRequest().method().name().toLowerCase();
+		ClientRequest request = context.getRequest();
+		return (request != null ? "http " + request.method().name().toLowerCase() : null);
 	}
 
 	@Override

spring-webflux/src/main/java/org/springframework/web/reactive/resource/ResourceUrlProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -94,7 +94,7 @@ public class ResourceUrlProvider implements ApplicationListener<ContextRefreshed
 	@Override
 	public void onApplicationEvent(ContextRefreshedEvent event) {
 		if (this.applicationContext == event.getApplicationContext() && this.handlerMap.isEmpty()) {
-			detectResourceHandlers(this.applicationContext);
+			detectResourceHandlers(event.getApplicationContext());
 		}
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/ConsumesRequestCondition.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -75,14 +75,14 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 	 * @param consumes as described in {@link RequestMapping#consumes()}
 	 * @param headers as described in {@link RequestMapping#headers()}
 	 */
-	public ConsumesRequestCondition(String[] consumes, String[] headers) {
+	public ConsumesRequestCondition(@Nullable String[] consumes, @Nullable String[] headers) {
 		this.expressions = parseExpressions(consumes, headers);
 		if (this.expressions.size() > 1) {
 			Collections.sort(this.expressions);
 		}
 	}
 
-	private static List<ConsumeMediaTypeExpression> parseExpressions(String[] consumes, String[] headers) {
+	private static List<ConsumeMediaTypeExpression> parseExpressions(@Nullable String[] consumes, @Nullable String[] headers) {
 		Set<ConsumeMediaTypeExpression> result = null;
 		if (!ObjectUtils.isEmpty(headers)) {
 			for (String header : headers) {

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/ProducesRequestCondition.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -81,7 +81,7 @@ public final class ProducesRequestCondition extends AbstractRequestCondition<Pro
 	 * @param produces expressions with syntax defined by {@link RequestMapping#produces()}
 	 * @param headers expressions with syntax defined by {@link RequestMapping#headers()}
 	 */
-	public ProducesRequestCondition(String[] produces, String[] headers) {
+	public ProducesRequestCondition(@Nullable String[] produces, @Nullable String[] headers) {
 		this(produces, headers, null);
 	}
 
@@ -92,15 +92,17 @@ public final class ProducesRequestCondition extends AbstractRequestCondition<Pro
 	 * @param headers expressions with syntax defined by {@link RequestMapping#headers()}
 	 * @param resolver used to determine requested content type
 	 */
-	public ProducesRequestCondition(String[] produces, String[] headers, RequestedContentTypeResolver resolver) {
+	public ProducesRequestCondition(
+			@Nullable String[] produces, @Nullable String[] headers, @Nullable RequestedContentTypeResolver resolver) {
+
 		this.expressions = parseExpressions(produces, headers);
 		if (this.expressions.size() > 1) {
 			Collections.sort(this.expressions);
 		}
-		this.contentTypeResolver = resolver != null ? resolver : DEFAULT_CONTENT_TYPE_RESOLVER;
+		this.contentTypeResolver = (resolver != null ? resolver : DEFAULT_CONTENT_TYPE_RESOLVER);
 	}
 
-	private List<ProduceMediaTypeExpression> parseExpressions(String[] produces, String[] headers) {
+	private List<ProduceMediaTypeExpression> parseExpressions(@Nullable String[] produces, @Nullable String[] headers) {
 		Set<ProduceMediaTypeExpression> result = null;
 		if (!ObjectUtils.isEmpty(headers)) {
 			for (String header : headers) {

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/AbstractNamedValueArgumentResolver.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.reactive.result.method.annotation;
 
+import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 import java.util.Map;
 import java.util.Objects;
@@ -200,7 +201,10 @@ public abstract class AbstractNamedValueArgumentResolver extends HandlerMethodAr
 		WebDataBinder binder = bindingContext.createDataBinder(exchange, namedValueInfo.name);
 		Class<?> parameterType = parameter.getParameterType();
 		if (KotlinDetector.isKotlinPresent() && KotlinDetector.isInlineClass(parameterType)) {
-			parameterType = BeanUtils.findPrimaryConstructor(parameterType).getParameterTypes()[0];
+			Constructor<?> ctor = BeanUtils.findPrimaryConstructor(parameterType);
+			if (ctor != null) {
+				parameterType = ctor.getParameterTypes()[0];
+			}
 		}
 		try {
 			value = binder.convertIfNecessary(value, parameterType, parameter);

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ModelInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -32,7 +32,6 @@ import org.springframework.core.ReactiveAdapter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotatedElementUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.ModelAttribute;
@@ -74,7 +73,6 @@ class ModelInitializer {
 	 * @param exchange the current exchange
 	 * @return a {@code Mono} for when the model is populated.
 	 */
-	@SuppressWarnings("Convert2MethodRef")
 	public Mono<Void> initModel(HandlerMethod handlerMethod, InitBinderBindingContext bindingContext,
 			ServerWebExchange exchange) {
 
@@ -124,7 +122,7 @@ class ModelInitializer {
 			ResolvableType type = handlerResult.getReturnType();
 			MethodParameter typeSource = handlerResult.getReturnTypeSource();
 			ReactiveAdapter adapter = this.adapterRegistry.getAdapter(type.resolve(), value);
-			if (isAsyncVoidType(type, typeSource, adapter)) {
+			if (adapter != null && isAsyncVoidType(type, typeSource, adapter)) {
 				return Mono.from(adapter.toPublisher(value));
 			}
 			String name = getAttributeName(typeSource);
@@ -134,10 +132,10 @@ class ModelInitializer {
 	}
 
 
-	private boolean isAsyncVoidType(ResolvableType type, MethodParameter typeSource, @Nullable ReactiveAdapter adapter) {
+	private boolean isAsyncVoidType(ResolvableType type, MethodParameter typeSource, ReactiveAdapter adapter) {
 		Method method = typeSource.getMethod();
-		return (adapter != null && (adapter.isNoValue() || type.resolveGeneric() == Void.class)) ||
+		return (adapter.isNoValue() || type.resolveGeneric() == Void.class || (method != null &&
-				(method != null && KotlinDetector.isSuspendingFunction(method) && typeSource.getParameterType() == void.class);
+				KotlinDetector.isSuspendingFunction(method) && typeSource.getParameterType() == void.class));
 	}
 
 	private String getAttributeName(MethodParameter param) {

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ResponseEntityResultHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -94,7 +94,6 @@ public class ResponseEntityResultHandler extends AbstractMessageWriterResultHand
 				isSupportedType(result.getReturnType().getGeneric().toClass());
 	}
 
-	@Nullable
 	private static Class<?> resolveReturnValueType(HandlerResult result) {
 		Class<?> valueType = result.getReturnType().toClass();
 		Object value = result.getReturnValue();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/ConsumesRequestCondition.java

@@ -76,14 +76,14 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 	 * @param consumes as described in {@link RequestMapping#consumes()}
 	 * @param headers as described in {@link RequestMapping#headers()}
 	 */
-	public ConsumesRequestCondition(String[] consumes, @Nullable String[] headers) {
+	public ConsumesRequestCondition(@Nullable String[] consumes, @Nullable String[] headers) {
 		this.expressions = parseExpressions(consumes, headers);
 		if (this.expressions.size() > 1) {
 			Collections.sort(this.expressions);
 		}
 	}
 
-	private static List<ConsumeMediaTypeExpression> parseExpressions(String[] consumes, @Nullable String[] headers) {
+	private static List<ConsumeMediaTypeExpression> parseExpressions(@Nullable String[] consumes, @Nullable String[] headers) {
 		Set<ConsumeMediaTypeExpression> result = null;
 		if (!ObjectUtils.isEmpty(headers)) {
 			for (String header : headers) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/ProducesRequestCondition.java

@@ -83,7 +83,7 @@ public final class ProducesRequestCondition extends AbstractRequestCondition<Pro
 	 * @param produces expressions with syntax defined by {@link RequestMapping#produces()}
 	 * @param headers expressions with syntax defined by {@link RequestMapping#headers()}
 	 */
-	public ProducesRequestCondition(String[] produces, @Nullable String[] headers) {
+	public ProducesRequestCondition(@Nullable String[] produces, @Nullable String[] headers) {
 		this(produces, headers, null);
 	}
 
@@ -94,17 +94,17 @@ public final class ProducesRequestCondition extends AbstractRequestCondition<Pro
 	 * @param headers expressions with syntax defined by {@link RequestMapping#headers()}
 	 * @param manager used to determine requested media types
 	 */
-	public ProducesRequestCondition(String[] produces, @Nullable String[] headers,
+	public ProducesRequestCondition(@Nullable String[] produces, @Nullable String[] headers,
 			@Nullable ContentNegotiationManager manager) {
 
 		this.expressions = parseExpressions(produces, headers);
 		if (this.expressions.size() > 1) {
 			Collections.sort(this.expressions);
 		}
-		this.contentNegotiationManager = manager != null ? manager : DEFAULT_CONTENT_NEGOTIATION_MANAGER;
+		this.contentNegotiationManager = (manager != null ? manager : DEFAULT_CONTENT_NEGOTIATION_MANAGER);
 	}
 
-	private List<ProduceMediaTypeExpression> parseExpressions(String[] produces, @Nullable String[] headers) {
+	private List<ProduceMediaTypeExpression> parseExpressions(@Nullable String[] produces, @Nullable String[] headers) {
 		Set<ProduceMediaTypeExpression> result = null;
 		if (!ObjectUtils.isEmpty(headers)) {
 			for (String header : headers) {