Nullability refinements and related polishing

See gh-32475

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");
-			if (isSameDeclaringClass(targetClassName)) {
+			Assert.state(this.declaringClass != null, "Static method reference must define a declaring class");
+			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)));
+			});
 		}
 
 		/**
@@ -240,12 +246,15 @@ public class ReflectionHintsPredicates {
 		 */
 		public Predicate<RuntimeHints> withAnyMemberCategory(MemberCategory... memberCategories) {
 			Assert.notEmpty(memberCategories, "'memberCategories' must not be empty");
-			return this.and(hints -> Arrays.stream(memberCategories)
-					.anyMatch(memberCategory -> getTypeHint(hints).getMemberCategories().contains(memberCategory)));
+			return and(hints -> {
+				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> {
 
 		protected final T executable;
@@ -289,6 +298,7 @@ public class ReflectionHintsPredicates {
 		}
 	}
 
+
 	public static class ConstructorHintPredicate extends ExecutableHintPredicate<Constructor<?>> {
 
 		ConstructorHintPredicate(Constructor<?> constructor) {
@@ -322,15 +332,17 @@ public class ReflectionHintsPredicates {
 
 		@Override
 		Predicate<RuntimeHints> exactMatch() {
-			return hints -> (hints.reflection().getTypeHint(this.executable.getDeclaringClass()) != null) &&
-					hints.reflection().getTypeHint(this.executable.getDeclaringClass()).constructors().anyMatch(executableHint -> {
-						List<TypeReference> parameters = TypeReference.listOf(this.executable.getParameterTypes());
-						return includes(executableHint, "<init>", parameters, this.executableMode);
-					});
+			return hints -> {
+				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> {
 
 		MethodHintPredicate(Method method) {
@@ -367,15 +379,17 @@ public class ReflectionHintsPredicates {
 
 		@Override
 		Predicate<RuntimeHints> exactMatch() {
-			return hints -> (hints.reflection().getTypeHint(this.executable.getDeclaringClass()) != null) &&
-					hints.reflection().getTypeHint(this.executable.getDeclaringClass()).methods().anyMatch(executableHint -> {
-						List<TypeReference> parameters = TypeReference.listOf(this.executable.getParameterTypes());
-						return includes(executableHint, this.executable.getName(), parameters, this.executableMode);
-					});
+			return hints -> {
+				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> {
 
 		private final Field field;
@@ -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,
-			Object... args) {
-		Assert.isTrue(KotlinDetector.isSuspendingFunction(method), "'method' must be a suspending function");
+	public static Publisher<?> invokeSuspendingFunction(
+			CoroutineContext context, Method method, @Nullable Object target, Object... args) {
+
+		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)
-				.stream()
+		MergedAnnotation<?> merged = MergedAnnotations.from(clazz, SearchStrategy.SUPERCLASS).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.
@@ -167,19 +167,21 @@ final class MergedAnnotationsCollection implements MergedAnnotations {
 		MergedAnnotation<A> result = null;
 		for (int i = 0; i < this.annotations.length; i++) {
 			MergedAnnotation<?> root = this.annotations[i];
-			AnnotationTypeMappings mappings = this.mappings[i];
-			for (int mappingIndex = 0; mappingIndex < mappings.size(); mappingIndex++) {
-				AnnotationTypeMapping mapping = mappings.get(mappingIndex);
-				if (!isMappingForType(mapping, requiredType)) {
-					continue;
-				}
-				MergedAnnotation<A> candidate = (mappingIndex == 0 ? (MergedAnnotation<A>) root :
-						TypeMappedAnnotation.createIfPossible(mapping, root, IntrospectionFailureLogger.INFO));
-				if (candidate != null && (predicate == null || predicate.test(candidate))) {
-					if (selector.isBestCandidate(candidate)) {
-						return candidate;
+			if (root != null) {
+				AnnotationTypeMappings mappings = this.mappings[i];
+				for (int mappingIndex = 0; mappingIndex < mappings.size(); mappingIndex++) {
+					AnnotationTypeMapping mapping = mappings.get(mappingIndex);
+					if (!isMappingForType(mapping, requiredType)) {
+						continue;
+					}
+					MergedAnnotation<A> candidate = (mappingIndex == 0 ? (MergedAnnotation<A>) root :
+							TypeMappedAnnotation.createIfPossible(mapping, root, IntrospectionFailureLogger.INFO));
+					if (candidate != null && (predicate == null || predicate.test(candidate))) {
+						if (selector.isBestCandidate(candidate)) {
+							return candidate;
+						}
+						result = (result != null ? selector.select(result, candidate) : candidate);
 					}
-					result = (result != null ? selector.select(result, candidate) : candidate);
 				}
 			}
 		}

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);
-					return;
+					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);
-				return;
+				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