Introduce ClassUtils.isVoidType() utility method

integration-tests/src/test/java/org/springframework/expression/spel/support/BeanFactoryTypeConverter.java

@@ -27,6 +27,7 @@
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.expression.TypeConverter;
+import org.springframework.util.ClassUtils;
 
 /**
  * Copied from Spring Integration for purposes of reproducing
@@ -91,7 +92,7 @@ public boolean canConvert(TypeDescriptor sourceTypeDescriptor, TypeDescriptor ta
 
 	@Override
 	public Object convertValue(Object value, TypeDescriptor sourceType, TypeDescriptor targetType) {
-		if (targetType.getType() == Void.class || targetType.getType() == void.class) {
+		if (ClassUtils.isVoidType(targetType.getType())) {
 			return null;
 		}
 		if (conversionService.canConvert(sourceType, targetType)) {

spring-core/src/main/java/org/springframework/util/ClassUtils.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.
@@ -549,6 +549,18 @@ public static Class<?> resolvePrimitiveIfNecessary(Class<?> clazz) {
 		return (clazz.isPrimitive() && clazz != void.class ? primitiveTypeToWrapperMap.get(clazz) : clazz);
 	}
 
+	/**
+	 * Determine if the given type represents either {@code Void} or {@code void}.
+	 * @param type the type to check
+	 * @return {@code true} if the type represents {@code Void} or {@code void}
+	 * @since 6.1.4
+	 * @see Void
+	 * @see Void#TYPE
+	 */
+	public static boolean isVoidType(Class<?> type) {
+		return (type == void.class || type == Void.class);
+	}
+
 	/**
 	 * Delegate for {@link org.springframework.beans.BeanUtils#isSimpleValueType}.
 	 * Also used by {@link ObjectUtils#nullSafeConciseToString}.
@@ -565,7 +577,7 @@ public static Class<?> resolvePrimitiveIfNecessary(Class<?> clazz) {
 	 * @since 6.1
 	 */
 	public static boolean isSimpleValueType(Class<?> type) {
-		return (Void.class != type && void.class != type &&
+		return (!isVoidType(type) &&
 				(isPrimitiveOrWrapper(type) ||
 				Enum.class.isAssignableFrom(type) ||
 				CharSequence.class.isAssignableFrom(type) ||

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 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.
@@ -41,6 +41,7 @@
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.MessagingException;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeType;
 
 /**
@@ -144,7 +145,7 @@ private Flux<DataBuffer> encodeContent(
 					ResolvableType.forInstance(content) : returnValueType);
 		}
 
-		if (elementType.resolve() == void.class || elementType.resolve() == Void.class) {
+		if (ClassUtils.isVoidType(elementType.resolve())) {
 			return Flux.from(publisher).cast(DataBuffer.class);
 		}
 

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultRSocketRequester.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.
@@ -37,6 +37,7 @@
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeType;
 
 /**
@@ -119,7 +120,7 @@ public RequestSpec metadata(Object metadata, @Nullable MimeType mimeType) {
 	}
 
 	private static boolean isVoid(ResolvableType elementType) {
-		return (Void.class.equals(elementType.resolve()) || void.class.equals(elementType.resolve()));
+		return ClassUtils.isVoidType(elementType.resolve());
 	}
 
 	private DataBufferFactory bufferFactory() {

spring-messaging/src/main/java/org/springframework/messaging/rsocket/service/RSocketServiceMethod.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.
@@ -38,6 +38,7 @@
 import org.springframework.messaging.rsocket.RSocketRequester;
 import org.springframework.messaging.rsocket.RSocketStrategies;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeType;
 import org.springframework.util.StringUtils;
 import org.springframework.util.StringValueResolver;
@@ -134,9 +135,7 @@ private static Function<RSocketRequestValues, Object> initResponseFunction(
 		Class<?> actualType = actualParam.getNestedParameterType();
 
 		Function<RSocketRequestValues, Publisher<?>> responseFunction;
-		if (actualType.equals(void.class) || actualType.equals(Void.class) ||
-				(reactiveAdapter != null && reactiveAdapter.isNoValue())) {
-
+		if (ClassUtils.isVoidType(actualType) || (reactiveAdapter != null && reactiveAdapter.isNoValue())) {
 			responseFunction = values -> {
 				RSocketRequester.RetrieveSpec retrieveSpec = initRequest(requester, values);
 				return (values.getPayload() == null && values.getPayloadValue() == null ?

spring-web/src/main/java/org/springframework/web/service/invoker/HttpServiceMethod.java

@@ -350,7 +350,7 @@ public static ResponseFunction create(HttpExchangeAdapter client, Method method)
 			Class<?> paramType = param.getNestedParameterType();
 
 			Function<HttpRequestValues, Object> responseFunction;
-			if (paramType.equals(void.class) || paramType.equals(Void.class)) {
+			if (ClassUtils.isVoidType(paramType)) {
 				responseFunction = requestValues -> {
 					client.exchange(requestValues);
 					return null;
@@ -436,7 +436,7 @@ public static ResponseFunction create(ReactorHttpExchangeAdapter client, Method
 			Class<?> actualType = isSuspending ? actualParam.getParameterType() : actualParam.getNestedParameterType();
 
 			Function<HttpRequestValues, Publisher<?>> responseFunction;
-			if (actualType.equals(void.class) || actualType.equals(Void.class)) {
+			if (ClassUtils.isVoidType(actualType)) {
 				responseFunction = client::exchangeForMono;
 			}
 			else if (reactiveAdapter != null && reactiveAdapter.isNoValue()) {

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/AbstractMessageWriterResultHandler.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.
@@ -38,6 +38,7 @@
 import org.springframework.http.converter.HttpMessageNotWritableException;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
 import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
@@ -155,7 +156,7 @@ protected Mono<Void> writeBody(@Nullable Object body, MethodParameter bodyParame
 			}
 		}
 
-		if (elementType.resolve() == void.class || elementType.resolve() == Void.class) {
+		if (ClassUtils.isVoidType(elementType.resolve())) {
 			return Mono.from((Publisher<Void>) publisher);
 		}
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandler.java

@@ -39,6 +39,7 @@
 import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 import org.springframework.ui.Model;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.reactive.BindingContext;
@@ -202,7 +203,7 @@ public Mono<Void> handleResult(ServerWebExchange exchange, HandlerResult result)
 						clazz = returnValue.getClass();
 					}
 
-					if (returnValue == NO_VALUE || clazz == void.class || clazz == Void.class) {
+					if (returnValue == NO_VALUE || ClassUtils.isVoidType(clazz)) {
 						viewsMono = resolveViews(getDefaultViewName(exchange), locale);
 					}
 					else if (CharSequence.class.isAssignableFrom(clazz) && !hasModelAnnotation(parameter)) {