JacksonAutoConfiguration should retain modules registered in Jackson2ObjectMapperBuilderCustomizer with higher precedence, rather than overwriting them

Author: nosan

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -306,7 +306,7 @@ private Field findPropertyNamingStrategyField(String fieldName) {
 			}
 
 			private void configureModules(Jackson2ObjectMapperBuilder builder) {
-				builder.modulesToInstall(this.modules.toArray(new Module[0]));
+				builder.modulesToInstall((modules) -> modules.addAll(this.modules));
 			}
 
 			private void configureLocale(Jackson2ObjectMapperBuilder builder) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfigurationTests.java

@@ -73,6 +73,8 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.Primary;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -324,6 +326,16 @@ void moduleBeansAndWellKnownModulesAreRegisteredWithTheObjectMapperBuilder() {
 		});
 	}
 
+	@Test
+	void customModulesRegisteredByBuilderCustomizerWithHighestPrecedenceShouldBeRetained() {
+		this.contextRunner.withUserConfiguration(CustomModuleJacksonBuilderCustomizerConfig.class).run((context) -> {
+			ObjectMapper objectMapper = context.getBean(Jackson2ObjectMapperBuilder.class).build();
+			assertThat(objectMapper.getRegisteredModuleIds()).contains("customizer-module");
+			// must be present because the customizer has higher precedence.
+			assertThat(objectMapper.getRegisteredModuleIds()).contains(JsonMixinModule.class.getName());
+		});
+	}
+
 	@Test
 	void defaultSerializationInclusion() {
 		this.contextRunner.run((context) -> {
@@ -592,6 +604,17 @@ Jackson2ObjectMapperBuilderCustomizer customDateFormat() {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CustomModuleJacksonBuilderCustomizerConfig {
+
+		@Bean
+		@Order(Ordered.HIGHEST_PRECEDENCE)
+		Jackson2ObjectMapperBuilderCustomizer customModuleCustomizer() {
+			return (builder) -> builder.modulesToInstall(new SimpleModule("customizer-module"));
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class ObjectMapperBuilderConsumerConfig {