Specify generic type nullness in spring-core

Also in spring-core-test.

See gh-34140

spring-core-test/src/main/java/org/springframework/core/test/tools/CompileWithForkedClassLoaderClassLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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 +37,7 @@ final class CompileWithForkedClassLoaderClassLoader extends ClassLoader {
 
 	private final ClassLoader testClassLoader;
 
-	private Function<String, byte[]> classResourceLookup = name -> null;
+	private Function<String, byte @Nullable []> classResourceLookup = name -> null;
 
 
 	public CompileWithForkedClassLoaderClassLoader(ClassLoader testClassLoader) {
@@ -48,7 +48,7 @@ final class CompileWithForkedClassLoaderClassLoader extends ClassLoader {
 
 	// Invoked reflectively by DynamicClassLoader
 	@SuppressWarnings("unused")
-	void setClassResourceLookup(Function<String, byte[]> classResourceLookup) {
+	void setClassResourceLookup(Function<String, byte @Nullable []> classResourceLookup) {
 		this.classResourceLookup = classResourceLookup;
 	}
 

spring-core-test/src/main/java/org/springframework/core/test/tools/DynamicClassLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -71,7 +71,7 @@ public class DynamicClassLoader extends ClassLoader {
 					"setClassResourceLookup", Function.class);
 			ReflectionUtils.makeAccessible(setClassResourceLookupMethod);
 			ReflectionUtils.invokeMethod(setClassResourceLookupMethod,
-					getParent(), (Function<String, byte[]>) this::findClassBytes);
+					getParent(), (Function<String, byte @Nullable []>) this::findClassBytes);
 			this.defineClassMethod = lookupMethod(parentClass,
 					"defineDynamicClass", String.class, byte[].class, int.class, int.class);
 			ReflectionUtils.makeAccessible(this.defineClassMethod);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -106,7 +106,7 @@ public interface MethodReference {
 		 * @param function the resolver function
 		 * @return a new {@link ArgumentCodeGenerator} instance backed by the function
 		 */
-		static ArgumentCodeGenerator from(Function<TypeName, CodeBlock> function) {
+		static ArgumentCodeGenerator from(Function<TypeName, @Nullable CodeBlock> function) {
 			return function::apply;
 		}
 

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

@@ -706,7 +706,7 @@ public class MethodParameter {
 		}
 		ParameterNameDiscoverer discoverer = this.parameterNameDiscoverer;
 		if (discoverer != null) {
-			String[] parameterNames = null;
+			@Nullable String[] parameterNames = null;
 			if (this.executable instanceof Method method) {
 				parameterNames = discoverer.getParameterNames(method);
 			}
@@ -865,7 +865,7 @@ public class MethodParameter {
 	 * @return the corresponding MethodParameter instance
 	 * @since 6.1
 	 */
-	public static MethodParameter forFieldAwareConstructor(Constructor<?> ctor, int parameterIndex, String fieldName) {
+	public static MethodParameter forFieldAwareConstructor(Constructor<?> ctor, int parameterIndex, @Nullable String fieldName) {
 		return new FieldAwareConstructorParameter(ctor, parameterIndex, fieldName);
 	}
 
@@ -877,7 +877,7 @@ public class MethodParameter {
 
 		private volatile Annotation @Nullable [] combinedAnnotations;
 
-		public FieldAwareConstructorParameter(Constructor<?> constructor, int parameterIndex, String fieldName) {
+		public FieldAwareConstructorParameter(Constructor<?> constructor, int parameterIndex, @Nullable String fieldName) {
 			super(constructor, parameterIndex);
 			this.parameterName = fieldName;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -19,12 +19,15 @@ package org.springframework.core;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 import java.util.concurrent.Flow;
 import java.util.function.Function;
 
+import io.smallrye.mutiny.Multi;
+import io.smallrye.mutiny.Uni;
 import org.jspecify.annotations.Nullable;
 import org.reactivestreams.FlowAdapters;
 import org.reactivestreams.Publisher;
@@ -380,13 +383,13 @@ public class ReactiveAdapterRegistry {
 						io.smallrye.mutiny.groups.MultiCreate.class, "publisher", Flow.Publisher.class);
 				registry.registerReactiveType(uniDesc,
 						uni -> FlowAdapters.toPublisher((Flow.Publisher<Object>)
-								ReflectionUtils.invokeMethod(uniToPublisher, ((io.smallrye.mutiny.Uni<?>) uni).convert())),
-						publisher -> ReflectionUtils.invokeMethod(uniPublisher, io.smallrye.mutiny.Uni.createFrom(),
-								FlowAdapters.toFlowPublisher(publisher)));
+								Objects.requireNonNull(ReflectionUtils.invokeMethod(uniToPublisher, ((Uni<?>) uni).convert()))),
+						publisher -> Objects.requireNonNull(ReflectionUtils.invokeMethod(uniPublisher, Uni.createFrom(),
+								FlowAdapters.toFlowPublisher(publisher))));
 				registry.registerReactiveType(multiDesc,
 						multi -> FlowAdapters.toPublisher((Flow.Publisher<Object>) multi),
-						publisher -> ReflectionUtils.invokeMethod(multiPublisher, io.smallrye.mutiny.Multi.createFrom(),
-								FlowAdapters.toFlowPublisher(publisher)));
+						publisher -> Objects.requireNonNull(ReflectionUtils.invokeMethod(multiPublisher, Multi.createFrom(),
+								FlowAdapters.toFlowPublisher(publisher))));
 			}
 			else {
 				// Mutiny 1 based on Reactive Streams

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -825,9 +825,9 @@ public class ResolvableType implements Serializable {
 	 * @see #getGenerics()
 	 * @see #resolve()
 	 */
-	public Class<?>[] resolveGenerics() {
+	public @Nullable Class<?>[] resolveGenerics() {
 		ResolvableType[] generics = getGenerics();
-		Class<?>[] resolvedGenerics = new Class<?>[generics.length];
+		@Nullable Class<?>[] resolvedGenerics = new Class<?>[generics.length];
 		for (int i = 0; i < generics.length; i++) {
 			resolvedGenerics[i] = generics[i].resolve();
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -205,7 +205,7 @@ final class SerializableTypeWrapper {
 				if (returnValue == null) {
 					return null;
 				}
-				Type[] result = new Type[((Type[]) returnValue).length];
+				@Nullable Type[] result = new Type[((Type[]) returnValue).length];
 				for (int i = 0; i < result.length; i++) {
 					result[i] = forTypeProvider(new MethodInvokeTypeProvider(this.provider, method, i));
 				}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -478,7 +478,7 @@ public abstract class AnnotatedElementUtils {
 	 * attributes from all annotations found, or {@code null} if not found
 	 * @see #getAllAnnotationAttributes(AnnotatedElement, String, boolean, boolean)
 	 */
-	public static @Nullable MultiValueMap<String, Object> getAllAnnotationAttributes(
+	public static MultiValueMap<String, @Nullable Object> getAllAnnotationAttributes(
 			AnnotatedElement element, String annotationName) {
 
 		return getAllAnnotationAttributes(element, annotationName, false, false);
@@ -502,7 +502,7 @@ public abstract class AnnotatedElementUtils {
 	 * @return a {@link MultiValueMap} keyed by attribute name, containing the annotation
 	 * attributes from all annotations found, or {@code null} if not found
 	 */
-	public static @Nullable MultiValueMap<String, Object> getAllAnnotationAttributes(AnnotatedElement element,
+	public static MultiValueMap<String, @Nullable Object> getAllAnnotationAttributes(AnnotatedElement element,
 			String annotationName, final boolean classValuesAsString, final boolean nestedAnnotationsAsMap) {
 
 		Adapt[] adaptations = Adapt.values(classValuesAsString, nestedAnnotationsAsMap);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -45,7 +45,7 @@ import org.springframework.util.StringUtils;
  * @see AnnotatedElementUtils
  */
 @SuppressWarnings("serial")
-public class AnnotationAttributes extends LinkedHashMap<String, Object> {
+public class AnnotationAttributes extends LinkedHashMap<String, @Nullable Object> {
 
 	private static final String UNKNOWN = "unknown";
 
@@ -83,7 +83,7 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 	 * @param map original source of annotation attribute <em>key-value</em> pairs
 	 * @see #fromMap(Map)
 	 */
-	public AnnotationAttributes(Map<String, Object> map) {
+	public AnnotationAttributes(Map<String, @Nullable Object> map) {
 		super(map);
 		this.annotationType = null;
 		this.displayName = UNKNOWN;
@@ -376,10 +376,10 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 
 	@Override
 	public String toString() {
-		Iterator<Map.Entry<String, Object>> entries = entrySet().iterator();
+		Iterator<Map.Entry<String, @Nullable Object>> entries = entrySet().iterator();
 		StringBuilder sb = new StringBuilder("{");
 		while (entries.hasNext()) {
-			Map.Entry<String, Object> entry = entries.next();
+			Map.Entry<String, @Nullable Object> entry = entries.next();
 			sb.append(entry.getKey());
 			sb.append('=');
 			sb.append(valueToString(entry.getValue()));
@@ -391,7 +391,7 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 		return sb.toString();
 	}
 
-	private String valueToString(Object value) {
+	private String valueToString(@Nullable Object value) {
 		if (value == this) {
 			return "(this Map)";
 		}
@@ -410,7 +410,7 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 	 * to the {@link #AnnotationAttributes(Map)} constructor.
 	 * @param map original source of annotation attribute <em>key-value</em> pairs
 	 */
-	public static @Nullable AnnotationAttributes fromMap(@Nullable Map<String, Object> map) {
+	public static @Nullable AnnotationAttributes fromMap(@Nullable Map<String, @Nullable Object> map) {
 		if (map == null) {
 			return null;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -27,6 +27,7 @@ import java.util.Set;
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.lang.Contract;
 import org.springframework.util.ConcurrentReferenceHashMap;
 
 /**
@@ -87,7 +88,7 @@ final class AnnotationTypeMappings {
 	}
 
 	private void addMetaAnnotationsToQueue(Deque<AnnotationTypeMapping> queue, AnnotationTypeMapping source) {
-		Annotation[] metaAnnotations = AnnotationsScanner.getDeclaredAnnotations(source.getAnnotationType(), false);
+		@Nullable Annotation[] metaAnnotations = AnnotationsScanner.getDeclaredAnnotations(source.getAnnotationType(), false);
 		for (Annotation metaAnnotation : metaAnnotations) {
 			if (!isMappable(source, metaAnnotation)) {
 				continue;
@@ -127,6 +128,7 @@ final class AnnotationTypeMappings {
 		}
 	}
 
+	@Contract("_, null -> false")
 	private boolean isMappable(AnnotationTypeMapping source, @Nullable Annotation metaAnnotation) {
 		return (metaAnnotation != null && !this.filter.matches(metaAnnotation) &&
 				!AnnotationFilter.PLAIN.matches(source.getAnnotationType()) &&

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -773,7 +773,7 @@ public abstract class AnnotationUtils {
 	 * @see #getAnnotationAttributes(Annotation, boolean, boolean)
 	 * @see #getAnnotationAttributes(AnnotatedElement, Annotation, boolean, boolean)
 	 */
-	public static Map<String, Object> getAnnotationAttributes(Annotation annotation) {
+	public static Map<String, @Nullable Object> getAnnotationAttributes(Annotation annotation) {
 		return getAnnotationAttributes(null, annotation);
 	}
 
@@ -791,7 +791,7 @@ public abstract class AnnotationUtils {
 	 * corresponding attribute values as values (never {@code null})
 	 * @see #getAnnotationAttributes(Annotation, boolean, boolean)
 	 */
-	public static Map<String, Object> getAnnotationAttributes(
+	public static Map<String, @Nullable Object> getAnnotationAttributes(
 			Annotation annotation, boolean classValuesAsString) {
 
 		return getAnnotationAttributes(annotation, classValuesAsString, false);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -54,7 +54,7 @@ interface AnnotationsProcessor<C, R> {
 	 * {@code null} elements)
 	 * @return a {@code non-null} result if no further processing is required
 	 */
-	@Nullable R doWithAnnotations(C context, int aggregateIndex, @Nullable Object source, Annotation[] annotations);
+	@Nullable R doWithAnnotations(C context, int aggregateIndex, @Nullable Object source, @Nullable Annotation[] annotations);
 
 	/**
 	 * Get the final result to be returned. By default this method returns

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -47,7 +47,7 @@ import org.springframework.util.ReflectionUtils;
  */
 abstract class AnnotationsScanner {
 
-	private static final Annotation[] NO_ANNOTATIONS = {};
+	private static final @Nullable Annotation[] NO_ANNOTATIONS = {};
 
 	private static final Method[] NO_METHODS = {};
 
@@ -55,7 +55,7 @@ abstract class AnnotationsScanner {
 	private static final Map<AnnotatedElement, Annotation[]> declaredAnnotationCache =
 			new ConcurrentReferenceHashMap<>(256);
 
-	private static final Map<Class<?>, Method[]> baseTypeMethodsCache =
+	private static final Map<Class<?>, @Nullable Method[]> baseTypeMethodsCache =
 			new ConcurrentReferenceHashMap<>(256);
 
 
@@ -114,7 +114,7 @@ abstract class AnnotationsScanner {
 			if (isWithoutHierarchy(source, Search.never)) {
 				return processElement(context, source, processor);
 			}
-			Annotation[] relevant = null;
+			@Nullable Annotation[] relevant = null;
 			int remaining = Integer.MAX_VALUE;
 			int aggregateIndex = 0;
 			Class<?> root = source;
@@ -123,7 +123,7 @@ abstract class AnnotationsScanner {
 				if (result != null) {
 					return result;
 				}
-				Annotation[] declaredAnns = getDeclaredAnnotations(source, true);
+				@Nullable Annotation[] declaredAnns = getDeclaredAnnotations(source, true);
 				if (declaredAnns.length > 0) {
 					if (relevant == null) {
 						relevant = root.getAnnotations();
@@ -133,6 +133,7 @@ abstract class AnnotationsScanner {
 						if (declaredAnns[i] != null) {
 							boolean isRelevant = false;
 							for (int relevantIndex = 0; relevantIndex < relevant.length; relevantIndex++) {
+								//noinspection DataFlowIssue
 								if (relevant[relevantIndex] != null &&
 										declaredAnns[i].annotationType() == relevant[relevantIndex].annotationType()) {
 									isRelevant = true;
@@ -181,7 +182,7 @@ abstract class AnnotationsScanner {
 			if (hasPlainJavaAnnotationsOnly(source)) {
 				return null;
 			}
-			Annotation[] annotations = getDeclaredAnnotations(source, false);
+			@Nullable Annotation[] annotations = getDeclaredAnnotations(source, false);
 			result = processor.doWithAnnotations(context, aggregateIndex[0], source, annotations);
 			if (result != null) {
 				return result;
@@ -320,16 +321,18 @@ abstract class AnnotationsScanner {
 		return null;
 	}
 
-	private static <C> Method[] getBaseTypeMethods(C context, Class<?> baseType) {
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
+	private static <C> @Nullable Method[] getBaseTypeMethods(C context, Class<?> baseType) {
 		if (baseType == Object.class || hasPlainJavaAnnotationsOnly(baseType)) {
 			return NO_METHODS;
 		}
 
-		Method[] methods = baseTypeMethodsCache.get(baseType);
+		@Nullable Method[] methods = baseTypeMethodsCache.get(baseType);
 		if (methods == null) {
 			methods = ReflectionUtils.getDeclaredMethods(baseType);
 			int cleared = 0;
 			for (int i = 0; i < methods.length; i++) {
+				//noinspection DataFlowIssue
 				if (Modifier.isPrivate(methods[i].getModifiers()) ||
 						hasPlainJavaAnnotationsOnly(methods[i]) ||
 						getDeclaredAnnotations(methods[i], false).length == 0) {
@@ -385,14 +388,14 @@ abstract class AnnotationsScanner {
 	private static <C, R> @Nullable R processMethodAnnotations(C context, int aggregateIndex, Method source,
 			AnnotationsProcessor<C, R> processor) {
 
-		Annotation[] annotations = getDeclaredAnnotations(source, false);
+		@Nullable Annotation[] annotations = getDeclaredAnnotations(source, false);
 		R result = processor.doWithAnnotations(context, aggregateIndex, source, annotations);
 		if (result != null) {
 			return result;
 		}
 		Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(source);
 		if (bridgedMethod != source) {
-			Annotation[] bridgedAnnotations = getDeclaredAnnotations(bridgedMethod, true);
+			@Nullable Annotation[] bridgedAnnotations = getDeclaredAnnotations(bridgedMethod, true);
 			for (int i = 0; i < bridgedAnnotations.length; i++) {
 				if (ObjectUtils.containsElement(annotations, bridgedAnnotations[i])) {
 					bridgedAnnotations[i] = null;
@@ -419,7 +422,7 @@ abstract class AnnotationsScanner {
 
 	@SuppressWarnings("unchecked")
 	static <A extends Annotation> @Nullable A getDeclaredAnnotation(AnnotatedElement source, Class<A> annotationType) {
-		Annotation[] annotations = getDeclaredAnnotations(source, false);
+		@Nullable Annotation[] annotations = getDeclaredAnnotations(source, false);
 		for (Annotation annotation : annotations) {
 			if (annotation != null && annotationType == annotation.annotationType()) {
 				return (A) annotation;
@@ -428,9 +431,10 @@ abstract class AnnotationsScanner {
 		return null;
 	}
 
-	static Annotation[] getDeclaredAnnotations(AnnotatedElement source, boolean defensive) {
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
+	static @Nullable Annotation[] getDeclaredAnnotations(AnnotatedElement source, boolean defensive) {
 		boolean cached = false;
-		Annotation[] annotations = declaredAnnotationCache.get(source);
+		@Nullable Annotation[] annotations = declaredAnnotationCache.get(source);
 		if (annotations != null) {
 			cached = true;
 		}
@@ -440,6 +444,7 @@ abstract class AnnotationsScanner {
 				boolean allIgnored = true;
 				for (int i = 0; i < annotations.length; i++) {
 					Annotation annotation = annotations[i];
+					//noinspection DataFlowIssue
 					if (isIgnorable(annotation.annotationType()) ||
 							!AttributeMethods.forAnnotationType(annotation.annotationType()).canLoad(annotation)) {
 						annotations[i] = null;
@@ -450,6 +455,7 @@ abstract class AnnotationsScanner {
 				}
 				annotations = (allIgnored ? NO_ANNOTATIONS : annotations);
 				if (source instanceof Class || source instanceof Member) {
+					//noinspection NullableProblems
 					declaredAnnotationCache.put(source, annotations);
 					cached = true;
 				}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -250,11 +250,13 @@ final class AttributeMethods {
 		return cache.computeIfAbsent(annotationType, AttributeMethods::compute);
 	}
 
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
 	private static AttributeMethods compute(Class<? extends Annotation> annotationType) {
 		Method[] methods = annotationType.getDeclaredMethods();
 		int size = methods.length;
 		for (int i = 0; i < methods.length; i++) {
 			if (!isAttributeMethod(methods[i])) {
+				//noinspection DataFlowIssue
 				methods[i] = null;
 				size--;
 			}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -26,6 +26,8 @@ import java.util.function.IntFunction;
 import java.util.stream.Collector;
 import java.util.stream.Collector.Characteristics;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.annotation.MergedAnnotation.Adapt;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -108,10 +110,10 @@ public abstract class MergedAnnotationCollectors {
 	 * annotations into a {@link LinkedMultiValueMap}
 	 * @see #toMultiValueMap(Function, MergedAnnotation.Adapt...)
 	 */
-	public static <A extends Annotation> Collector<MergedAnnotation<A>, ?, MultiValueMap<String, Object>> toMultiValueMap(
+	public static <A extends Annotation> Collector<MergedAnnotation<A>, ? extends @Nullable Object, @Nullable MultiValueMap<String, @Nullable Object>> toMultiValueMap(
 			Adapt... adaptations) {
 
-		return toMultiValueMap(Function.identity(), adaptations);
+		return toMultiValueMap((MultiValueMap<String, @Nullable Object> t) -> t, adaptations);
 	}
 
 	/**
@@ -126,14 +128,14 @@ public abstract class MergedAnnotationCollectors {
 	 * annotations into a {@link LinkedMultiValueMap}
 	 * @see #toMultiValueMap(MergedAnnotation.Adapt...)
 	 */
-	public static <A extends Annotation> Collector<MergedAnnotation<A>, ?, MultiValueMap<String, Object>> toMultiValueMap(
-			Function<MultiValueMap<String, Object>, MultiValueMap<String, Object>> finisher,
+	public static <A extends Annotation> Collector<MergedAnnotation<A>, ? extends @Nullable Object, @Nullable MultiValueMap<String, @Nullable Object>> toMultiValueMap(
+			Function<MultiValueMap<String, @Nullable Object>, @Nullable MultiValueMap<String, @Nullable Object>> finisher,
 			Adapt... adaptations) {
 
 		Characteristics[] characteristics = (isSameInstance(finisher, Function.identity()) ?
 				IDENTITY_FINISH_CHARACTERISTICS : NO_CHARACTERISTICS);
 		return Collector.of(LinkedMultiValueMap::new,
-				(map, annotation) -> annotation.asMap(adaptations).forEach(map::add),
+				(MultiValueMap<String, @Nullable Object> map, MergedAnnotation<A> annotation) -> annotation.asMap(adaptations).forEach(map::add),
 				MergedAnnotationCollectors::combiner, finisher, characteristics);
 	}
 
@@ -157,7 +159,7 @@ public abstract class MergedAnnotationCollectors {
 	 * <p>This method is only invoked if the {@link java.util.stream.Stream} is
 	 * processed in {@linkplain java.util.stream.Stream#parallel() parallel}.
 	 */
-	private static <K, V> MultiValueMap<K, V> combiner(MultiValueMap<K, V> map, MultiValueMap<K, V> additions) {
+	private static <K, V> MultiValueMap<K, @Nullable V> combiner(MultiValueMap<K, @Nullable V> map, MultiValueMap<K, @Nullable V> additions) {
 		map.addAll(additions);
 		return map;
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -23,8 +23,6 @@ import java.util.Set;
 import java.util.function.Function;
 import java.util.function.Predicate;
 
-import org.jspecify.annotations.Nullable;
-
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -126,7 +124,8 @@ public abstract class MergedAnnotationPredicates {
 
 		private boolean hasLastValue;
 
-		private @Nullable Object lastValue;
+		@SuppressWarnings("NullAway.Init")
+		private Object lastValue;
 
 		FirstRunOfPredicate(Function<? super MergedAnnotation<A>, ?> valueExtractor) {
 			Assert.notNull(valueExtractor, "Value extractor must not be null");
@@ -134,7 +133,7 @@ public abstract class MergedAnnotationPredicates {
 		}
 
 		@Override
-		public boolean test(@Nullable MergedAnnotation<A> annotation) {
+		public boolean test(MergedAnnotation<A> annotation) {
 			if (!this.hasLastValue) {
 				this.hasLastValue = true;
 				this.lastValue = this.valueExtractor.apply(annotation);
@@ -162,7 +161,7 @@ public abstract class MergedAnnotationPredicates {
 		}
 
 		@Override
-		public boolean test(@Nullable MergedAnnotation<A> annotation) {
+		public boolean test(MergedAnnotation<A> annotation) {
 			K key = this.keyExtractor.apply(annotation);
 			return this.seen.add(key);
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -29,6 +29,7 @@ import java.util.function.Predicate;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 
 /**
@@ -309,7 +310,7 @@ final class TypeMappedAnnotations implements MergedAnnotations {
 
 		@Override
 		public @Nullable Boolean doWithAnnotations(Object requiredType, int aggregateIndex,
-				@Nullable Object source, Annotation[] annotations) {
+				@Nullable Object source, @Nullable Annotation[] annotations) {
 
 			for (Annotation annotation : annotations) {
 				if (annotation != null) {
@@ -388,7 +389,7 @@ final class TypeMappedAnnotations implements MergedAnnotations {
 
 		@Override
 		public @Nullable MergedAnnotation<A> doWithAnnotations(Object type, int aggregateIndex,
-				@Nullable Object source, Annotation[] annotations) {
+				@Nullable Object source, @Nullable Annotation[] annotations) {
 
 			for (Annotation annotation : annotations) {
 				if (annotation != null && !annotationFilter.matches(annotation)) {
@@ -450,24 +451,24 @@ final class TypeMappedAnnotations implements MergedAnnotations {
 
 		@Override
 		public @Nullable List<Aggregate> doWithAnnotations(Object criteria, int aggregateIndex,
-				@Nullable Object source, Annotation[] annotations) {
+				@Nullable Object source, @Nullable Annotation[] annotations) {
 
 			this.aggregates.add(createAggregate(aggregateIndex, source, annotations));
 			return null;
 		}
 
-		private Aggregate createAggregate(int aggregateIndex, @Nullable Object source, Annotation[] annotations) {
+		private Aggregate createAggregate(int aggregateIndex, @Nullable Object source, @Nullable Annotation[] annotations) {
 			List<Annotation> aggregateAnnotations = getAggregateAnnotations(annotations);
 			return new Aggregate(aggregateIndex, source, aggregateAnnotations);
 		}
 
-		private List<Annotation> getAggregateAnnotations(Annotation[] annotations) {
+		private List<Annotation> getAggregateAnnotations(@Nullable Annotation[] annotations) {
 			List<Annotation> result = new ArrayList<>(annotations.length);
 			addAggregateAnnotations(result, annotations);
 			return result;
 		}
 
-		private void addAggregateAnnotations(List<Annotation> aggregateAnnotations, Annotation[] annotations) {
+		private void addAggregateAnnotations(List<Annotation> aggregateAnnotations, @Nullable Annotation[] annotations) {
 			for (Annotation annotation : annotations) {
 				if (annotation != null && !annotationFilter.matches(annotation)) {
 					Annotation[] repeatedAnnotations = repeatableContainers.findRepeatedAnnotations(annotation);
@@ -482,7 +483,7 @@ final class TypeMappedAnnotations implements MergedAnnotations {
 		}
 
 		@Override
-		public List<Aggregate> finish(@Nullable List<Aggregate> processResult) {
+		public @NonNull List<Aggregate> finish(@Nullable List<Aggregate> processResult) {
 			return this.aggregates;
 		}
 	}

spring-core/src/main/java/org/springframework/core/io/support/SpringFactoriesLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -584,11 +584,11 @@ public class SpringFactoriesLoader {
 		 * @param function the resolver function
 		 * @return a new {@link ArgumentResolver} instance backed by the function
 		 */
-		static ArgumentResolver from(Function<Class<?>, Object> function) {
+		static ArgumentResolver from(Function<Class<?>, @Nullable Object> function) {
 			return new ArgumentResolver() {
 				@SuppressWarnings("unchecked")
 				@Override
-				public <T> T resolve(Class<T> type) {
+				public <T> @Nullable T resolve(Class<T> type) {
 					return (T) function.apply(type);
 				}
 			};

spring-core/src/main/java/org/springframework/core/type/AnnotatedTypeMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -87,7 +87,7 @@ public interface AnnotatedTypeMetadata {
 	 * as map key (for example, "location") and the attribute's value as map value; or
 	 * {@code null} if no matching annotation is found
 	 */
-	default @Nullable Map<String, Object> getAnnotationAttributes(String annotationName) {
+	default @Nullable Map<String, @Nullable Object> getAnnotationAttributes(String annotationName) {
 		return getAnnotationAttributes(annotationName, false);
 	}
 
@@ -106,7 +106,7 @@ public interface AnnotatedTypeMetadata {
 	 * as map key (for example, "location") and the attribute's value as map value; or
 	 * {@code null} if no matching annotation is found
 	 */
-	default @Nullable Map<String, Object> getAnnotationAttributes(String annotationName,
+	default @Nullable Map<String, @Nullable Object> getAnnotationAttributes(String annotationName,
 			boolean classValuesAsString) {
 
 		MergedAnnotation<Annotation> annotation = getAnnotations().get(annotationName,
@@ -129,7 +129,7 @@ public interface AnnotatedTypeMetadata {
 	 * map value; or {@code null} if no matching annotation is found
 	 * @see #getAllAnnotationAttributes(String, boolean)
 	 */
-	default @Nullable MultiValueMap<String, Object> getAllAnnotationAttributes(String annotationName) {
+	default @Nullable MultiValueMap<String, @Nullable Object> getAllAnnotationAttributes(String annotationName) {
 		return getAllAnnotationAttributes(annotationName, false);
 	}
 
@@ -148,7 +148,7 @@ public interface AnnotatedTypeMetadata {
 	 * map value; or {@code null} if no matching annotation is found
 	 * @see #getAllAnnotationAttributes(String)
 	 */
-	default @Nullable MultiValueMap<String, Object> getAllAnnotationAttributes(
+	default @Nullable MultiValueMap<String, @Nullable Object> getAllAnnotationAttributes(
 			String annotationName, boolean classValuesAsString) {
 
 		Adapt[] adaptations = Adapt.values(classValuesAsString, true);
@@ -156,7 +156,7 @@ public interface AnnotatedTypeMetadata {
 				.filter(MergedAnnotationPredicates.unique(MergedAnnotation::getMetaTypes))
 				.map(MergedAnnotation::withNonMergedAttributes)
 				.collect(MergedAnnotationCollectors.toMultiValueMap(
-						map -> (map.isEmpty() ? null : map), adaptations));
+						(MultiValueMap<String, @Nullable Object> map) -> (map.isEmpty() ? null : map), adaptations));
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/type/StandardAnnotationMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -105,7 +105,7 @@ public class StandardAnnotationMetadata extends StandardClassMetadata implements
 	}
 
 	@Override
-	public @Nullable Map<String, Object> getAnnotationAttributes(String annotationName, boolean classValuesAsString) {
+	public @Nullable Map<String, @Nullable Object> getAnnotationAttributes(String annotationName, boolean classValuesAsString) {
 		if (this.nestedAnnotationsAsMap) {
 			return AnnotationMetadata.super.getAnnotationAttributes(annotationName, classValuesAsString);
 		}
@@ -114,7 +114,8 @@ public class StandardAnnotationMetadata extends StandardClassMetadata implements
 	}
 
 	@Override
-	public @Nullable MultiValueMap<String, Object> getAllAnnotationAttributes(String annotationName, boolean classValuesAsString) {
+	@SuppressWarnings("NullAway") // Null-safety of Java super method not yet managed
+	public @Nullable MultiValueMap<String, @Nullable Object> getAllAnnotationAttributes(String annotationName, boolean classValuesAsString) {
 		if (this.nestedAnnotationsAsMap) {
 			return AnnotationMetadata.super.getAllAnnotationAttributes(annotationName, classValuesAsString);
 		}

spring-core/src/main/java/org/springframework/core/type/StandardMethodMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -131,7 +131,7 @@ public class StandardMethodMetadata implements MethodMetadata {
 	}
 
 	@Override
-	public @Nullable Map<String, Object> getAnnotationAttributes(String annotationName, boolean classValuesAsString) {
+	public @Nullable Map<String, @Nullable Object> getAnnotationAttributes(String annotationName, boolean classValuesAsString) {
 		if (this.nestedAnnotationsAsMap) {
 			return MethodMetadata.super.getAnnotationAttributes(annotationName, classValuesAsString);
 		}
@@ -140,7 +140,8 @@ public class StandardMethodMetadata implements MethodMetadata {
 	}
 
 	@Override
-	public @Nullable MultiValueMap<String, Object> getAllAnnotationAttributes(String annotationName, boolean classValuesAsString) {
+	@SuppressWarnings("NullAway") // Null-safety of Java super method not yet managed
+	public @Nullable MultiValueMap<String, @Nullable Object> getAllAnnotationAttributes(String annotationName, boolean classValuesAsString) {
 		if (this.nestedAnnotationsAsMap) {
 			return MethodMetadata.super.getAllAnnotationAttributes(annotationName, classValuesAsString);
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -64,7 +64,7 @@ public abstract class CollectionUtils {
 	 * @return whether the given Collection is empty
 	 */
 	@Contract("null -> true")
-	public static boolean isEmpty(@Nullable Collection<?> collection) {
+	public static boolean isEmpty(@Nullable Collection<? extends @Nullable Object> collection) {
 		return (collection == null || collection.isEmpty());
 	}
 
@@ -75,7 +75,7 @@ public abstract class CollectionUtils {
 	 * @return whether the given Map is empty
 	 */
 	@Contract("null -> true")
-	public static boolean isEmpty(@Nullable Map<?, ?> map) {
+	public static boolean isEmpty(@Nullable Map<?, ? extends @Nullable Object> map) {
 		return (map == null || map.isEmpty());
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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 +20,8 @@ import java.lang.reflect.Array;
 import java.util.Collection;
 import java.util.Iterator;
 
+import org.jspecify.annotations.Nullable;
+
 
 /**
  * Composite collection that combines two other collections. This type is only
@@ -83,10 +85,10 @@ class CompositeCollection<E> implements Collection<E> {
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
-	public <T> T[] toArray(T[] a) {
+	@SuppressWarnings({"unchecked","NullAway"}) // Overridden method does not define nullness
+	public <T> @Nullable T[] toArray(@Nullable T[] a) {
 		int size = this.size();
-		T[] result;
+		@Nullable T[] result;
 		if (a.length >= size) {
 			result = a;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -456,7 +456,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 		 * Array of references indexed using the low order bits from the hash.
 		 * This property should only be set along with {@code resizeThreshold}.
 		 */
-		private volatile Reference<K, V>[] references;
+		private volatile @Nullable Reference<K, V>[] references;
 
 		/**
 		 * The total number of references contained in this segment. This includes chained
@@ -485,7 +485,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 				return null;
 			}
 			// Use a local copy to protect against other threads writing
-			Reference<K, V>[] references = this.references;
+			@Nullable Reference<K, V>[] references = this.references;
 			int index = getIndex(hash, references);
 			Reference<K, V> head = references[index];
 			return findInChain(head, key, hash);
@@ -641,7 +641,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 			}
 		}
 
-		private @Nullable Reference<K, V> findInChain(Reference<K, V> ref, @Nullable Object key, int hash) {
+		private @Nullable Reference<K, V> findInChain(@Nullable Reference<K, V> ref, @Nullable Object key, int hash) {
 			Reference<K, V> currRef = ref;
 			while (currRef != null) {
 				if (currRef.getHash() == hash) {
@@ -663,7 +663,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 			return new Reference[size];
 		}
 
-		private int getIndex(int hash, Reference<K, V>[] references) {
+		private int getIndex(int hash, @Nullable Reference<K, V>[] references) {
 			return (hash & (references.length - 1));
 		}
 
@@ -879,7 +879,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 
 		private int referenceIndex;
 
-		private Reference<K, V> @Nullable [] references;
+		private @Nullable Reference<K, V> @Nullable [] references;
 
 		private @Nullable Reference<K, V> reference;
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -49,7 +49,7 @@ public class MethodInvoker {
 
 	private @Nullable String staticMethod;
 
-	private Object @Nullable [] arguments;
+	private @Nullable Object @Nullable [] arguments;
 
 	/** The method we will call. */
 	private @Nullable Method methodObject;
@@ -127,14 +127,14 @@ public class MethodInvoker {
 	 * Set arguments for the method invocation. If this property is not set,
 	 * or the Object array is of length 0, a method with no arguments is assumed.
 	 */
-	public void setArguments(Object @Nullable ... arguments) {
+	public void setArguments(@Nullable Object... arguments) {
 		this.arguments = arguments;
 	}
 
 	/**
 	 * Return the arguments for the method invocation.
 	 */
-	public Object[] getArguments() {
+	public @Nullable Object[] getArguments() {
 		return (this.arguments != null ? this.arguments : EMPTY_ARGUMENTS);
 	}
 
@@ -166,7 +166,7 @@ public class MethodInvoker {
 		Assert.notNull(targetClass, "Either 'targetClass' or 'targetObject' is required");
 		Assert.notNull(targetMethod, "Property 'targetMethod' is required");
 
-		Object[] arguments = getArguments();
+		@Nullable Object[] arguments = getArguments();
 		Class<?>[] argTypes = new Class<?>[arguments.length];
 		for (int i = 0; i < arguments.length; ++i) {
 			argTypes[i] = (arguments[i] != null ? arguments[i].getClass() : Object.class);
@@ -206,7 +206,7 @@ public class MethodInvoker {
 	 */
 	protected @Nullable Method findMatchingMethod() {
 		String targetMethod = getTargetMethod();
-		Object[] arguments = getArguments();
+		@Nullable Object[] arguments = getArguments();
 		int argCount = arguments.length;
 
 		Class<?> targetClass = getTargetClass();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -29,7 +29,7 @@ import org.jspecify.annotations.Nullable;
  * @param <K> the key type
  * @param <V> the value element type
  */
-public interface MultiValueMap<K, V> extends Map<K, List<V>> {
+public interface MultiValueMap<K, V extends @Nullable Object> extends Map<K, List<V>> {
 
 	/**
 	 * Return the first value for the given key.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -188,7 +188,7 @@ public abstract class ObjectUtils {
 	 * @param element the element to check for
 	 * @return whether the element has been found in the given array
 	 */
-	public static boolean containsElement(Object @Nullable [] array, Object element) {
+	public static boolean containsElement(@Nullable Object @Nullable [] array, @Nullable Object element) {
 		if (array == null) {
 			return false;
 		}
@@ -266,7 +266,7 @@ public abstract class ObjectUtils {
 	 * @return the new array (of the same component type; never {@code null})
 	 * @since 6.0
 	 */
-	public static <A, O extends A> A[] addObjectToArray(A @Nullable [] array, @Nullable O obj, int position) {
+	public static <A, O extends A> @Nullable A[] addObjectToArray(A @Nullable [] array, @Nullable O obj, int position) {
 		Class<?> componentType = Object.class;
 		if (array != null) {
 			componentType = array.getClass().componentType();
@@ -276,7 +276,7 @@ public abstract class ObjectUtils {
 		}
 		int newArrayLength = (array != null ? array.length + 1 : 1);
 		@SuppressWarnings("unchecked")
-		A[] newArray = (A[]) Array.newInstance(componentType, newArrayLength);
+		@Nullable A[] newArray = (A[]) Array.newInstance(componentType, newArrayLength);
 		if (array != null) {
 			System.arraycopy(array, 0, newArray, 0, position);
 			System.arraycopy(array, position, newArray, position + 1, array.length - position);
@@ -651,7 +651,7 @@ public abstract class ObjectUtils {
 	 * @param array the array to build a String representation for
 	 * @return a String representation of {@code array}
 	 */
-	public static String nullSafeToString(Object @Nullable [] array) {
+	public static String nullSafeToString(@Nullable Object @Nullable [] array) {
 		if (array == null) {
 			return NULL_STRING;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -1038,12 +1038,12 @@ public abstract class StringUtils {
 	 * @param array the original {@code String} array (potentially empty)
 	 * @return the resulting array (of the same size) with trimmed elements
 	 */
-	public static String[] trimArrayElements(String[] array) {
+	public static @Nullable String[] trimArrayElements(@Nullable String[] array) {
 		if (ObjectUtils.isEmpty(array)) {
 			return array;
 		}
 
-		String[] result = new String[array.length];
+		@Nullable String[] result = new String[array.length];
 		for (int i = 0; i < array.length; i++) {
 			String element = array[i];
 			result[i] = (element != null ? element.trim() : null);

spring-core/src/main/java/org/springframework/util/function/SingletonSupplier.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -22,6 +22,7 @@ import java.util.function.Supplier;
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 
 /**
@@ -38,11 +39,11 @@ import org.springframework.util.Assert;
  * @since 5.1
  * @param <T> the type of results supplied by this supplier
  */
-public class SingletonSupplier<T> implements Supplier<T> {
+public class SingletonSupplier<T> implements Supplier<@Nullable T> {
 
-	private final @Nullable Supplier<? extends T> instanceSupplier;
+	private final @Nullable Supplier<? extends @Nullable T> instanceSupplier;
 
-	private final @Nullable Supplier<? extends T> defaultSupplier;
+	private final @Nullable Supplier<? extends @Nullable T> defaultSupplier;
 
 	private volatile @Nullable T singletonInstance;
 
@@ -58,7 +59,7 @@ public class SingletonSupplier<T> implements Supplier<T> {
 	 * @param instance the singleton instance (potentially {@code null})
 	 * @param defaultSupplier the default supplier as a fallback
 	 */
-	public SingletonSupplier(@Nullable T instance, Supplier<? extends T> defaultSupplier) {
+	public SingletonSupplier(@Nullable T instance, Supplier<? extends @Nullable T> defaultSupplier) {
 		this.instanceSupplier = null;
 		this.defaultSupplier = defaultSupplier;
 		this.singletonInstance = instance;
@@ -70,17 +71,17 @@ public class SingletonSupplier<T> implements Supplier<T> {
 	 * @param instanceSupplier the immediate instance supplier
 	 * @param defaultSupplier the default supplier as a fallback
 	 */
-	public SingletonSupplier(@Nullable Supplier<? extends T> instanceSupplier, Supplier<? extends T> defaultSupplier) {
+	public SingletonSupplier(@Nullable Supplier<? extends @Nullable T> instanceSupplier, Supplier<? extends @Nullable T> defaultSupplier) {
 		this.instanceSupplier = instanceSupplier;
 		this.defaultSupplier = defaultSupplier;
 	}
 
-	private SingletonSupplier(Supplier<? extends T> supplier) {
+	private SingletonSupplier(Supplier<? extends @Nullable T> supplier) {
 		this.instanceSupplier = supplier;
 		this.defaultSupplier = null;
 	}
 
-	private SingletonSupplier(T singletonInstance) {
+	private SingletonSupplier(@Nullable T singletonInstance) {
 		this.instanceSupplier = null;
 		this.defaultSupplier = null;
 		this.singletonInstance = singletonInstance;
@@ -141,6 +142,7 @@ public class SingletonSupplier<T> implements Supplier<T> {
 	 * @param instance the singleton instance (potentially {@code null})
 	 * @return the singleton supplier, or {@code null} if the instance was {@code null}
 	 */
+	@Contract("null -> null; !null -> !null")
 	public static <T> @Nullable SingletonSupplier<T> ofNullable(@Nullable T instance) {
 		return (instance != null ? new SingletonSupplier<>(instance) : null);
 	}
@@ -159,7 +161,8 @@ public class SingletonSupplier<T> implements Supplier<T> {
 	 * @param supplier the instance supplier (potentially {@code null})
 	 * @return the singleton supplier, or {@code null} if the instance supplier was {@code null}
 	 */
-	public static <T> @Nullable SingletonSupplier<T> ofNullable(@Nullable Supplier<T> supplier) {
+	@Contract("null -> null; !null -> !null")
+	public static <T> @Nullable SingletonSupplier<T> ofNullable(@Nullable Supplier<? extends @Nullable T> supplier) {
 		return (supplier != null ? new SingletonSupplier<>(supplier) : null);
 	}
 

spring-core/src/main/java/org/springframework/util/function/SupplierUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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 +20,8 @@ import java.util.function.Supplier;
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.lang.Contract;
+
 /**
  * Convenience utilities for {@link java.util.function.Supplier} handling.
  *
@@ -35,6 +37,7 @@ public abstract class SupplierUtils {
 	 * @param supplier the supplier to resolve
 	 * @return the supplier's result, or {@code null} if none
 	 */
+	@Contract("null -> null; !null -> !null")
 	public static <T> @Nullable T resolve(@Nullable Supplier<T> supplier) {
 		return (supplier != null ? supplier.get() : null);
 	}

spring-core/src/test/java/org/springframework/core/annotation/AnnotationsScannerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -29,6 +29,7 @@ import java.util.Objects;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
@@ -469,13 +470,13 @@ class AnnotationsScannerTests {
 				new AnnotationsProcessor<Object, String>() {
 
 					@Override
-					public String doWithAggregate(Object context, int aggregateIndex) {
+					public @NonNull String doWithAggregate(Object context, int aggregateIndex) {
 						return "";
 					}
 
 					@Override
-					public String doWithAnnotations(Object context, int aggregateIndex,
-							@Nullable Object source, Annotation[] annotations) {
+					public @NonNull String doWithAnnotations(Object context, int aggregateIndex,
+							@Nullable Object source, @Nullable Annotation @Nullable [] annotations) {
 						throw new IllegalStateException("Should not call");
 					}
 
@@ -501,13 +502,13 @@ class AnnotationsScannerTests {
 				new AnnotationsProcessor<Object, String>() {
 
 					@Override
-					public String doWithAnnotations(Object context, int aggregateIndex,
-							@Nullable Object source, Annotation[] annotations) {
+					public @NonNull String doWithAnnotations(Object context, int aggregateIndex,
+							@Nullable Object source, @Nullable Annotation @Nullable [] annotations) {
 						return "K";
 					}
 
 					@Override
-					public String finish(@Nullable String result) {
+					public @NonNull String finish(@Nullable String result) {
 						return "O" + result;
 					}