Fix context class resolution for nested types

This commit introduces ContextClassRequestBodyAdvice which adds a
"contextClass" hint allowing to resolve generics for Optional,
HttpEntity or ServerSentEvent container types.

Closes spring-projectsgh-36111

Author: sdeleuze

spring-web/src/main/java/org/springframework/http/converter/AbstractJacksonHttpMessageConverter.java

@@ -313,7 +313,8 @@ public boolean canWrite(ResolvableType type, Class<?> valueClass, @Nullable Medi
 	public Object read(ResolvableType type, HttpInputMessage inputMessage, @Nullable Map<String, Object> hints)
 			throws IOException, HttpMessageNotReadableException {
 
-		Class<?> contextClass = (type.getSource() instanceof MethodParameter parameter ? parameter.getContainingClass() : null);
+		Class<?> contextClass = (type.getSource() instanceof MethodParameter parameter ? parameter.getContainingClass() :
+				(hints != null ? (Class<?>) hints.get("contextClass") : null));
 		JavaType javaType = getJavaType(type.getType(), contextClass);
 		return readJavaType(javaType, inputMessage, hints);
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupport.java

@@ -83,6 +83,7 @@
 import org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter;
 import org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter;
 import org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver;
+import org.springframework.web.servlet.mvc.method.annotation.ContextClassRequestBodyAdvice;
 import org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver;
 import org.springframework.web.servlet.mvc.method.annotation.JsonViewRequestBodyAdvice;
 import org.springframework.web.servlet.mvc.method.annotation.JsonViewResponseBodyAdvice;
@@ -661,6 +662,7 @@ public RequestMappingHandlerAdapter requestMappingHandlerAdapter(
 			List<ResponseBodyAdvice<?>> responseBodyAdvices = new ArrayList<>(2);
 			if (JACKSON_PRESENT || JACKSON_2_PRESENT) {
 				requestBodyAdvices.add(new JsonViewRequestBodyAdvice());
+				requestBodyAdvices.add(new ContextClassRequestBodyAdvice());
 				responseBodyAdvices.add(new JsonViewResponseBodyAdvice());
 			}
 			if (KOTLIN_REFLECT_PRESENT && KOTLIN_SERIALIZATION_PRESENT) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ContextClassRequestBodyAdvice.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2002-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.servlet.mvc.method.annotation;
+
+import java.lang.reflect.Type;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Optional;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.codec.ServerSentEvent;
+import org.springframework.http.converter.AbstractJacksonHttpMessageConverter;
+import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.SmartHttpMessageConverter;
+
+/**
+ * A {@link RequestBodyAdvice} implementation that adds a {@code "contextClass"} hint for {@link Optional},
+ * {@link HttpEntity} and {@link ServerSentEvent} container types.
+ *
+ * @author Sebastien Deleuze
+ * @since 7.0.3
+ */
+public class ContextClassRequestBodyAdvice extends RequestBodyAdviceAdapter {
+
+	@Override
+	public boolean supports(MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
+		if (!AbstractJacksonHttpMessageConverter.class.isAssignableFrom(converterType)) {
+			return false;
+		}
+		Class<?> parameterType = parameter.getParameterType();
+		return Optional.class.isAssignableFrom(parameterType) || HttpEntity.class.isAssignableFrom(parameterType) ||
+				ServerSentEvent.class.isAssignableFrom(parameterType);
+	}
+
+	@Override
+	public @Nullable Map<String, Object> determineReadHints(MethodParameter parameter, Type targetType,
+			Class<? extends SmartHttpMessageConverter<?>> converterType) {
+
+		return Collections.singletonMap("contextClass", parameter.getContainingClass());
+	}
+}

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupportTests.java

@@ -79,6 +79,7 @@
 import org.springframework.web.servlet.handler.HandlerExceptionResolverComposite;
 import org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver;
 import org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver;
+import org.springframework.web.servlet.mvc.method.annotation.ContextClassRequestBodyAdvice;
 import org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver;
 import org.springframework.web.servlet.mvc.method.annotation.JsonViewRequestBodyAdvice;
 import org.springframework.web.servlet.mvc.method.annotation.JsonViewResponseBodyAdvice;
@@ -208,11 +209,12 @@ void requestMappingHandlerAdapter() {
 		DirectFieldAccessor fieldAccessor = new DirectFieldAccessor(adapter);
 		@SuppressWarnings("unchecked")
 		List<Object> bodyAdvice = (List<Object>) fieldAccessor.getPropertyValue("requestResponseBodyAdvice");
-		assertThat(bodyAdvice).hasSize(4);
+		assertThat(bodyAdvice).hasSize(5);
 		assertThat(bodyAdvice.get(0).getClass()).isEqualTo(JsonViewRequestBodyAdvice.class);
-		assertThat(bodyAdvice.get(1).getClass()).isEqualTo(KotlinRequestBodyAdvice.class);
-		assertThat(bodyAdvice.get(2).getClass()).isEqualTo(JsonViewResponseBodyAdvice.class);
-		assertThat(bodyAdvice.get(3).getClass()).isEqualTo(KotlinResponseBodyAdvice.class);
+		assertThat(bodyAdvice.get(1).getClass()).isEqualTo(ContextClassRequestBodyAdvice.class);
+		assertThat(bodyAdvice.get(2).getClass()).isEqualTo(KotlinRequestBodyAdvice.class);
+		assertThat(bodyAdvice.get(3).getClass()).isEqualTo(JsonViewResponseBodyAdvice.class);
+		assertThat(bodyAdvice.get(4).getClass()).isEqualTo(KotlinResponseBodyAdvice.class);
 	}
 
 	@Test

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/HttpEntityMethodProcessorTests.java

@@ -30,7 +30,6 @@
 import jakarta.servlet.http.HttpServletResponse;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.MethodParameter;
@@ -152,7 +151,6 @@ void resolveGenericArgument() throws Exception {
 	}
 
 	@Test
-	@Disabled("Determine why this fails with JacksonJsonHttpMessageConverter but passes with MappingJackson2HttpMessageConverter")
 	void resolveArgumentTypeVariable() throws Exception {
 		Method method = MySimpleParameterizedController.class.getMethod("handleDto", HttpEntity.class);
 		HandlerMethod handlerMethod = new HandlerMethod(new MySimpleParameterizedController(), method);
@@ -164,7 +162,9 @@ void resolveArgumentTypeVariable() throws Exception {
 
 		List<HttpMessageConverter<?>> converters = new ArrayList<>();
 		converters.add(new JacksonJsonHttpMessageConverter());
-		HttpEntityMethodProcessor processor = new HttpEntityMethodProcessor(converters);
+		List<Object> requestResponseBodyAdvice = new ArrayList<>();
+		requestResponseBodyAdvice.add(new ContextClassRequestBodyAdvice());
+		HttpEntityMethodProcessor processor = new HttpEntityMethodProcessor(converters, requestResponseBodyAdvice);
 
 		@SuppressWarnings("unchecked")
 		HttpEntity<SimpleBean> result = (HttpEntity<SimpleBean>)