Do not use the Thread Context ClassLoader to load jackson modules.

Fixes #2921

Signed-off-by: Eric Bottard <[email protected]>

Author: ericbottard

spring-ai-commons/pom.xml

@@ -106,6 +106,11 @@
 			<artifactId>jackson-module-kotlin</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>com.fasterxml.jackson.datatype</groupId>
+			<artifactId>jackson-datatype-jsr310</artifactId>
+			<scope>test</scope>
+		</dependency>
 
 	</dependencies>
 

spring-ai-commons/src/main/java/org/springframework/ai/util/JacksonUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * Copyright 2023-2025 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.
@@ -23,7 +23,6 @@
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.KotlinDetector;
-import org.springframework.util.ClassUtils;
 
 /**
  * Utility methods for Jackson.
@@ -43,8 +42,8 @@ public abstract class JacksonUtils {
 	public static List<Module> instantiateAvailableModules() {
 		List<Module> modules = new ArrayList<>();
 		try {
-			Class<? extends com.fasterxml.jackson.databind.Module> jdk8ModuleClass = (Class<? extends Module>) ClassUtils
-				.forName("com.fasterxml.jackson.datatype.jdk8.Jdk8Module", null);
+			Class<? extends com.fasterxml.jackson.databind.Module> jdk8ModuleClass = (Class<? extends Module>) Class
+				.forName("com.fasterxml.jackson.datatype.jdk8.Jdk8Module");
 			com.fasterxml.jackson.databind.Module jdk8Module = BeanUtils.instantiateClass(jdk8ModuleClass);
 			modules.add(jdk8Module);
 		}
@@ -53,8 +52,8 @@ public static List<Module> instantiateAvailableModules() {
 		}
 
 		try {
-			Class<? extends com.fasterxml.jackson.databind.Module> javaTimeModuleClass = (Class<? extends Module>) ClassUtils
-				.forName("com.fasterxml.jackson.datatype.jsr310.JavaTimeModule", null);
+			Class<? extends com.fasterxml.jackson.databind.Module> javaTimeModuleClass = (Class<? extends Module>) Class
+				.forName("com.fasterxml.jackson.datatype.jsr310.JavaTimeModule");
 			com.fasterxml.jackson.databind.Module javaTimeModule = BeanUtils.instantiateClass(javaTimeModuleClass);
 			modules.add(javaTimeModule);
 		}
@@ -63,8 +62,8 @@ public static List<Module> instantiateAvailableModules() {
 		}
 
 		try {
-			Class<? extends com.fasterxml.jackson.databind.Module> parameterNamesModuleClass = (Class<? extends Module>) ClassUtils
-				.forName("com.fasterxml.jackson.module.paramnames.ParameterNamesModule", null);
+			Class<? extends com.fasterxml.jackson.databind.Module> parameterNamesModuleClass = (Class<? extends Module>) Class
+				.forName("com.fasterxml.jackson.module.paramnames.ParameterNamesModule");
 			com.fasterxml.jackson.databind.Module parameterNamesModule = BeanUtils
 				.instantiateClass(parameterNamesModuleClass);
 			modules.add(parameterNamesModule);
@@ -76,8 +75,8 @@ public static List<Module> instantiateAvailableModules() {
 		// Kotlin present?
 		if (KotlinDetector.isKotlinPresent()) {
 			try {
-				Class<? extends com.fasterxml.jackson.databind.Module> kotlinModuleClass = (Class<? extends Module>) ClassUtils
-					.forName("com.fasterxml.jackson.module.kotlin.KotlinModule", null);
+				Class<? extends com.fasterxml.jackson.databind.Module> kotlinModuleClass = (Class<? extends Module>) Class
+					.forName("com.fasterxml.jackson.module.kotlin.KotlinModule");
 				Module kotlinModule = BeanUtils.instantiateClass(kotlinModuleClass);
 				modules.add(kotlinModule);
 			}

spring-ai-commons/src/test/java/org/springframework/ai/util/JacksonUtilsTests.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2025-2025 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.
+ * 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.ai.util;
+
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class JacksonUtilsTests {
+
+	/*
+	 * Make sure that JacksonUtils use the correct classloader to load modules. See
+	 * https://github.com/spring-projects/spring-ai/issues/2921
+	 */
+	@Test
+	void usesCorrectClassLoader() throws JsonProcessingException, ClassNotFoundException {
+		ClassLoader previousLoader = Thread.currentThread().getContextClassLoader();
+		try {
+			// This parent CL cannot see the clazz class below. But this shouldn't matter.
+			Thread.currentThread().setContextClassLoader(getClass().getClassLoader().getParent());
+			// Should work whatever the current Thread context CL is
+			var jsonMapper = JsonMapper.builder().addModules(JacksonUtils.instantiateAvailableModules()).build();
+			Class<?> clazz = getClass().getClassLoader().loadClass(getClass().getName() + "$Cell");
+			var output = jsonMapper.readValue("{\"name\":\"Amoeba\",\"lifespan\":\"PT42S\"}", clazz);
+			assertThat(output).isEqualTo(new Cell("Amoeba", Duration.of(42L, ChronoUnit.SECONDS)));
+
+		}
+		finally {
+			Thread.currentThread().setContextClassLoader(previousLoader);
+		}
+
+	}
+
+	record Cell(String name, Duration lifespan) {
+	}
+
+}