Specify generic type nullness in spring-core

Also in spring-core-test.

See spring-projectsgh-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 @@ public CompileWithForkedClassLoaderClassLoader(ClassLoader testClassLoader) {
 
 	// 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 DynamicClassLoader(ClassLoader parent, ClassFiles classFiles, ResourceFil
 					"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 @@ static ArgumentCodeGenerator of(Class<?> argumentType, String argumentCode) {
 		 * @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 void initParameterNameDiscovery(@Nullable ParameterNameDiscoverer paramet
 		}
 		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 @@ private static int validateIndex(Executable executable, int parameterIndex) {
 	 * @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 @@ private static class FieldAwareConstructorParameter extends 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 @@
 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 @@ void registerAdapters(ReactiveAdapterRegistry registry) {
 						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 @@ else if (this.type instanceof ParameterizedType parameterizedType) {
 	 * @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 @@ else if (Type[].class == method.getReturnType() && ObjectUtils.isEmpty(args)) {
 				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 static <A extends Annotation> Set<A> getMergedRepeatableAnnotations(
 	 * 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 static <A extends Annotation> Set<A> getMergedRepeatableAnnotations(
 	 * @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 @@
  * @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 AnnotationAttributes(int initialCapacity) {
 	 * @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 @@ private <T> T getRequiredAttribute(String attributeName, Class<T> expectedType)
 
 	@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 String toString() {
 		return sb.toString();
 	}
 
-	private String valueToString(Object value) {
+	private String valueToString(@Nullable Object value) {
 		if (value == this) {
 			return "(this Map)";
 		}
@@ -410,7 +410,7 @@ private String valueToString(Object value) {
 	 * 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 org.jspecify.annotations.Nullable;
 
+import org.springframework.lang.Contract;
 import org.springframework.util.ConcurrentReferenceHashMap;
 
 /**
@@ -87,7 +88,7 @@ private void addAllMappings(Class<? extends Annotation> annotationType,
 	}
 
 	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 @@ private void addIfPossible(Deque<AnnotationTypeMapping> queue, @Nullable Annotat
 		}
 	}
 
+	@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 static void validateAnnotation(Annotation annotation) {
 	 * @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 static Map<String, Object> getAnnotationAttributes(Annotation annotation)
 	 * 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