MVC auto-configuration does not back off when `<mvc:annotation-driven>` is used resulting in a BeanDefinitionOverrideException for mvcContentNegotiationManager

[thomas-worm-datev]

Using spring boot 2.1.3:

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.3.RELEASE</version>
	</parent>`

with

		<!-- 
		
		***********************
		* Spring dependencies *
		***********************
		
		-->
	
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework.ws</groupId>
			<artifactId>spring-ws-core</artifactId>
		</dependency>
		
		<dependency>
			<groupId>org.springframework.ws</groupId>
			<artifactId>spring-ws-support</artifactId>
		</dependency>
		
		<dependency>
			<groupId>org.apache.httpcomponents</groupId>
			<artifactId>httpclient</artifactId>
		</dependency>

		<!-- 
				
		************************
		* Swagger dependencies *
		************************
		
		-->

		<dependency>
			<groupId>io.swagger</groupId>
			<artifactId>swagger-core</artifactId>
			<version>1.5.9</version>
		</dependency>

		<dependency>
			<groupId>io.swagger.core.v3</groupId>
			<artifactId>swagger-core</artifactId>
			<version>2.0.7</version>
		</dependency>
		
		<!-- 
		
		*******************************
		* Aspect oriented programming *
		*******************************
		
		 -->
		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjweaver</artifactId>
		</dependency>

I get

 .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.3.RELEASE)

2019-03-31 21:08:10.332  INFO 10564 --- [           main] d.d.a.b.api.Application                  : Starting Application v0.0.1-SNAPSHOT on VAA2DAE009 with PID 10564 (D:\git\build-and-qa-manager-api_spring\target\build-and-qa-manager-api-0.0.1-SNAPSHOT.jar started by T08958A in D:\git\build-and-qa-manager-api_spring)
2019-03-31 21:08:10.341 DEBUG 10564 --- [           main] d.d.a.b.api.Application                  : Running with Spring Boot v2.1.3.RELEASE, Spring v5.1.5.RELEASE
2019-03-31 21:08:10.343  INFO 10564 --- [           main] d.d.a.b.api.Application                  : No active profile set, falling back to default profiles: default
2019-03-31 21:08:12.050  WARN 10564 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.support.BeanDefinitionOverrideException: Invalid bean definition with name 'mvcContentNegotiationManager' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Cannot register bean definition [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$EnableWebMvcConfiguration; factoryMethodName=mvcContentNegotiationManager; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]] for bean 'mvcContentNegotiationManager': There is already [Root bean: class [org.springframework.web.accept.ContentNegotiationManagerFactoryBean]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] bound.
2019-03-31 21:08:12.068  INFO 10564 --- [           main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-03-31 21:08:12.072 ERROR 10564 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   :

***************************
APPLICATION FAILED TO START
***************************

Description:

The bean 'mvcContentNegotiationManager', defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class], could not be registered. A bean with that name has already been defined in null and overriding is disabled.

Action:

Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

There should be not BeanDefinitionOverrideException with the starter from spring boot.

I tried to set following in application.properties:

logging.level.de.datev.alm.build_and_qa_manager.api = DEBUG
spring.main.allow-bean-definition-overriding = true

but I got same exception.

[wilkinsona]

Can you please provide a minimal example that reproduces the problem?

[thomas-worm-datev]

Hi @wilkinsona

You can find the minimal example on
https://github.com/thomas-worm-datev/bootstrap-starter-problem-example

Best regards,
Thomas

[wilkinsona]

Thanks for the sample. It starts successfully for me if I add spring.main.allow-bean-definition-overriding=true to src/main/resources/application.properties.

The problem is caused by your use of XML-based configuration for Spring MVC and Spring Boot's auto-configuration for Spring MVC. Auto-configuration expects Java-based configuration to be used. It will back off if you've used @EnableWebMvc or declared your own sub-class of WebMvcConfigurationSupport. We can consider a change so that the auto-configuration also backs of when <mvc:annotation-driven /> is used to enable Spring MVC, but I'm not sure that it's worthwhile given how unusual your configuration is. Let's see what the rest of the team thinks.

Regardless of what we decide to do, I would recommend switching to Java-based configuration when using Spring Boot. Auto-configuration will configure a RestTemplate, Spring MVC, and a task executor for you so your XML file and XmlConfiguration.java can be removed from your application. You may also want to consider removing CodeConfiguration.java and using the auto-configured ObjectMapper instead.

[philwebb]

Unfortunately I don't think the extra complexity required to detect XML based configuration would be a particularly good use of our time. I think this is the first time I've seen such a request, so I'm tempted to leave this as a known limitation of our auto-configuration conditions.

[philwebb]

We discussed this as a team and we've decided to leave this as a known limitation.