Move spring.mvc.converters.preferred-json-mapper to spring.http

This commit deprecates spring.mvc.converters.preferred-json-mapper
and replaces it with spring.http.converters.preferred-json-mapper.
If both properties are specified, the latter takes precedence.

Closes gh-44925

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/ConditionalOnPreferredJsonMapper.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2012-2025 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.boot.autoconfigure.http;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Conditional;
+
+/**
+ * {@link Conditional @Conditional} that matches based on the preferred JSON mapper. A
+ * preference is expressed using the {@code spring.http.converters.preferred-json-mapper}
+ * configuration property, falling back to the
+ * {@code spring.mvc.converters.preferred-json-mapper} configuration property. When no
+ * preference is expressed Jackson is preferred by default.
+ *
+ * @author Andy Wilkinson
+ */
+@Conditional(OnPreferredJsonMapperCondition.class)
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Documented
+@interface ConditionalOnPreferredJsonMapper {
+
+	JsonMapper value();
+
+	enum JsonMapper {
+
+		GSON,
+
+		JACKSON,
+
+		JSONB,
+
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/GsonHttpMessageConvertersConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -22,8 +22,8 @@ import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.condition.NoneNestedConditions;
+import org.springframework.boot.autoconfigure.http.ConditionalOnPreferredJsonMapper.JsonMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
@@ -61,8 +61,7 @@ class GsonHttpMessageConvertersConfiguration {
 			super(ConfigurationPhase.REGISTER_BEAN);
 		}
 
-		@ConditionalOnProperty(name = HttpMessageConvertersAutoConfiguration.PREFERRED_MAPPER_PROPERTY,
-				havingValue = "gson")
+		@ConditionalOnPreferredJsonMapper(JsonMapper.GSON)
 		static class GsonPreferred {
 
 		}
@@ -85,8 +84,7 @@ class GsonHttpMessageConvertersConfiguration {
 
 		}
 
-		@ConditionalOnProperty(name = HttpMessageConvertersAutoConfiguration.PREFERRED_MAPPER_PROPERTY,
-				havingValue = "jsonb")
+		@ConditionalOnPreferredJsonMapper(JsonMapper.JSONB)
 		static class JsonbPreferred {
 
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/HttpMessageConvertersAutoConfiguration.java

@@ -66,8 +66,6 @@ import org.springframework.http.converter.StringHttpMessageConverter;
 @ImportRuntimeHints(HttpMessageConvertersAutoConfigurationRuntimeHints.class)
 public class HttpMessageConvertersAutoConfiguration {
 
-	static final String PREFERRED_MAPPER_PROPERTY = "spring.mvc.converters.preferred-json-mapper";
-
 	@Bean
 	@ConditionalOnMissingBean
 	public HttpMessageConverters messageConverters(ObjectProvider<HttpMessageConverter<?>> converters) {

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/JacksonHttpMessageConvertersConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -22,7 +22,7 @@ import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.http.ConditionalOnPreferredJsonMapper.JsonMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
@@ -40,8 +40,7 @@ class JacksonHttpMessageConvertersConfiguration {
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnClass(ObjectMapper.class)
 	@ConditionalOnBean(ObjectMapper.class)
-	@ConditionalOnProperty(name = HttpMessageConvertersAutoConfiguration.PREFERRED_MAPPER_PROPERTY,
-			havingValue = "jackson", matchIfMissing = true)
+	@ConditionalOnPreferredJsonMapper(JsonMapper.JACKSON)
 	static class MappingJackson2HttpMessageConverterConfiguration {
 
 		@Bean

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/JsonbHttpMessageConvertersConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -22,7 +22,7 @@ import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.http.ConditionalOnPreferredJsonMapper.JsonMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
@@ -60,8 +60,7 @@ class JsonbHttpMessageConvertersConfiguration {
 			super(ConfigurationPhase.REGISTER_BEAN);
 		}
 
-		@ConditionalOnProperty(name = HttpMessageConvertersAutoConfiguration.PREFERRED_MAPPER_PROPERTY,
-				havingValue = "jsonb")
+		@ConditionalOnPreferredJsonMapper(JsonMapper.JSONB)
 		static class JsonbPreferred {
 
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/OnPreferredJsonMapperCondition.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2012-2025 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.boot.autoconfigure.http;
+
+import java.util.Locale;
+
+import org.springframework.boot.autoconfigure.condition.ConditionMessage;
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.boot.autoconfigure.http.ConditionalOnPreferredJsonMapper.JsonMapper;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.env.Environment;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+
+/**
+ * {@link SpringBootCondition} for
+ * {@link ConditionalOnPreferredJsonMapper @ConditionalOnPreferredJsonMapper}.
+ *
+ * @author Andy Wilkinson
+ */
+class OnPreferredJsonMapperCondition extends SpringBootCondition {
+
+	private static final String PREFERRED_MAPPER_PROPERTY = "spring.http.converters.preferred-json-mapper";
+
+	@Deprecated(since = "3.5.0", forRemoval = true)
+	private static final String DEPRECATED_PREFERRED_MAPPER_PROPERTY = "spring.mvc.converters.preferred-json-mapper";
+
+	@Override
+	public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
+		JsonMapper conditionMapper = metadata.getAnnotations()
+			.get(ConditionalOnPreferredJsonMapper.class)
+			.getEnum("value", JsonMapper.class);
+		ConditionOutcome outcome = getMatchOutcome(context.getEnvironment(), PREFERRED_MAPPER_PROPERTY,
+				conditionMapper);
+		if (outcome != null) {
+			return outcome;
+		}
+		outcome = getMatchOutcome(context.getEnvironment(), DEPRECATED_PREFERRED_MAPPER_PROPERTY, conditionMapper);
+		if (outcome != null) {
+			return outcome;
+		}
+		ConditionMessage message = ConditionMessage
+			.forCondition(ConditionalOnPreferredJsonMapper.class, conditionMapper.name())
+			.because("no property was configured and Jackson is the default");
+		return (conditionMapper == JsonMapper.JACKSON) ? ConditionOutcome.match(message)
+				: ConditionOutcome.noMatch(message);
+	}
+
+	private ConditionOutcome getMatchOutcome(Environment environment, String key, JsonMapper conditionMapper) {
+		String property = environment.getProperty(key);
+		if (property == null) {
+			return null;
+		}
+		JsonMapper configuredMapper = JsonMapper.valueOf(property.toUpperCase(Locale.ROOT));
+		ConditionMessage message = ConditionMessage
+			.forCondition(ConditionalOnPreferredJsonMapper.class, configuredMapper.name())
+			.because("property '%s' had the value '%s'".formatted(key, property));
+		return (configuredMapper == conditionMapper) ? ConditionOutcome.match(message)
+				: ConditionOutcome.noMatch(message);
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -1615,11 +1615,8 @@
     {
       "name": "spring.http.converters.preferred-json-mapper",
       "type": "java.lang.String",
-      "description": "Preferred JSON mapper to use for HTTP message conversion. By default, auto-detected according to the environment.",
-      "deprecation": {
-        "replacement": "spring.mvc.converters.preferred-json-mapper",
-        "level": "error"
-      }
+      "defaultValue": "jackson",
+      "description": "Preferred JSON mapper to use for HTTP message conversion. By default, auto-detected according to the environment. Supported values are 'jackson', 'gson', and 'jsonb'. When other json mapping libraries (such as kotlinx.serialization) are present, use a custom HttpMessageConverters bean to control the preferred mapper."
     },
     {
       "name": "spring.http.encoding.charset",
@@ -2107,7 +2104,11 @@
       "name": "spring.mvc.converters.preferred-json-mapper",
       "type": "java.lang.String",
       "defaultValue": "jackson",
-      "description": "Preferred JSON mapper to use for HTTP message conversion. By default, auto-detected according to the environment. Supported values are 'jackson', 'gson', and 'jsonb'. When other json mapping libraries (such as kotlinx.serialization) are present, use a custom HttpMessageConverters bean to control the preferred mapper."
+      "description": "Preferred JSON mapper to use for HTTP message conversion. By default, auto-detected according to the environment. Supported values are 'jackson', 'gson', and 'jsonb'. When other json mapping libraries (such as kotlinx.serialization) are present, use a custom HttpMessageConverters bean to control the preferred mapper.",
+      "deprecation": {
+        "replacement": "spring.http.converters.preferred-json-mapper",
+        "level": "error"
+      }
     },
     {
       "name": "spring.mvc.date-format",

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/http/HttpMessageConvertersAutoConfigurationTests.java

@@ -32,7 +32,9 @@ import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConf
 import org.springframework.boot.autoconfigure.http.JacksonHttpMessageConvertersConfiguration.MappingJackson2HttpMessageConverterConfiguration;
 import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration;
+import org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.logging.LogLevel;
 import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
@@ -130,12 +132,41 @@ class HttpMessageConvertersAutoConfigurationTests {
 
 	@Test
 	void gsonCanBePreferred() {
-		allOptionsRunner().withPropertyValues("spring.mvc.converters.preferred-json-mapper:gson").run((context) -> {
-			assertConverterBeanExists(context, GsonHttpMessageConverter.class, "gsonHttpMessageConverter");
-			assertConverterBeanRegisteredWithHttpMessageConverters(context, GsonHttpMessageConverter.class);
-			assertThat(context).doesNotHaveBean(JsonbHttpMessageConverter.class);
-			assertThat(context).doesNotHaveBean(MappingJackson2HttpMessageConverter.class);
-		});
+		allOptionsRunner().withInitializer(ConditionEvaluationReportLoggingListener.forLogLevel(LogLevel.INFO))
+			.withPropertyValues("spring.http.converters.preferred-json-mapper:gson")
+			.run((context) -> {
+				assertConverterBeanExists(context, GsonHttpMessageConverter.class, "gsonHttpMessageConverter");
+				assertConverterBeanRegisteredWithHttpMessageConverters(context, GsonHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(JsonbHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(MappingJackson2HttpMessageConverter.class);
+			});
+	}
+
+	@Test
+	@Deprecated(since = "3.5.0", forRemoval = true)
+	void gsonCanBePreferredWithDeprecatedProperty() {
+		allOptionsRunner().withInitializer(ConditionEvaluationReportLoggingListener.forLogLevel(LogLevel.INFO))
+			.withPropertyValues("spring.mvc.converters.preferred-json-mapper:gson")
+			.run((context) -> {
+				assertConverterBeanExists(context, GsonHttpMessageConverter.class, "gsonHttpMessageConverter");
+				assertConverterBeanRegisteredWithHttpMessageConverters(context, GsonHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(JsonbHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(MappingJackson2HttpMessageConverter.class);
+			});
+	}
+
+	@Test
+	@Deprecated(since = "3.5.0", forRemoval = true)
+	void gsonCanBePreferredWithNonDeprecatedPropertyTakingPrecedence() {
+		allOptionsRunner().withInitializer(ConditionEvaluationReportLoggingListener.forLogLevel(LogLevel.INFO))
+			.withPropertyValues("spring.http.converters.preferred-json-mapper:gson",
+					"spring.mvc.converters.preferred-json-mapper:jackson")
+			.run((context) -> {
+				assertConverterBeanExists(context, GsonHttpMessageConverter.class, "gsonHttpMessageConverter");
+				assertConverterBeanRegisteredWithHttpMessageConverters(context, GsonHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(JsonbHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(MappingJackson2HttpMessageConverter.class);
+			});
 	}
 
 	@Test
@@ -169,6 +200,31 @@ class HttpMessageConvertersAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	@Deprecated(since = "3.5.0", forRemoval = true)
+	void jsonbCanBePreferredWithDeprecatedProperty() {
+		allOptionsRunner().withPropertyValues("spring.http.converters.preferred-json-mapper:jsonb").run((context) -> {
+			assertConverterBeanExists(context, JsonbHttpMessageConverter.class, "jsonbHttpMessageConverter");
+			assertConverterBeanRegisteredWithHttpMessageConverters(context, JsonbHttpMessageConverter.class);
+			assertThat(context).doesNotHaveBean(GsonHttpMessageConverter.class);
+			assertThat(context).doesNotHaveBean(MappingJackson2HttpMessageConverter.class);
+		});
+	}
+
+	@Test
+	@Deprecated(since = "3.5.0", forRemoval = true)
+	void jsonbCanBePreferredWithNonDeprecatedPropertyTakingPrecedence() {
+		allOptionsRunner()
+			.withPropertyValues("spring.http.converters.preferred-json-mapper:jsonb",
+					"spring.mvc.converters.preferred-json-mapper:gson")
+			.run((context) -> {
+				assertConverterBeanExists(context, JsonbHttpMessageConverter.class, "jsonbHttpMessageConverter");
+				assertConverterBeanRegisteredWithHttpMessageConverters(context, JsonbHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(GsonHttpMessageConverter.class);
+				assertThat(context).doesNotHaveBean(MappingJackson2HttpMessageConverter.class);
+			});
+	}
+
 	@Test
 	void stringDefaultConverter() {
 		this.contextRunner.run(assertConverter(StringHttpMessageConverter.class, "stringHttpMessageConverter"));