Bean with same name error when extending a bean defining configuration class

Question

So, I got this class that belongs to a external library (so I can't modify it):

@Configuration
@EnableWebMvc
@Slf4j
public class WebConfigParent implements WebMvcConfigurer {

private final ObjectMapper objectMapper;

public WebConfigParent(ObjectMapper objectMapper) {
    this.objectMapper = objectMapper;
}

@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    converters.add(new ResourceHttpMessageConverter());
    converters.add(new StringHttpMessageConverter());
    converters.add(new ByteArrayHttpMessageConverter());
    converters.add(mappingJackson2HttpMessageConverter());
}

@Bean //this is the issue!
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
    return new MappingJackson2HttpMessageConverter(objectMapper);
}

Now, my class:

@Configuration
public class WebConfigChild extends WebConfigParent {


public WebConfigChild(ObjectMapper objectMapper) {
    super(objectMapper);
}

Fails because of:

The bean 'mappingJackson2HttpMessageConverter', defined in class path resource [../WebConfigParent], could not be registered. A bean with that name has already been defined in class path resource [../WebConfigChild.class] and overriding is disabled.

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

I know it's dangerous to use the override setting (which, by the way, works) but I have no idea on how to prevent this behavior! I tried re-defining the method in the child class like this:

@Bean(name="anotherMapper")
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
    return super.mappingJackson2HttpMessageConverter();
}

but still the same error...why??

Answer 1

Since WebConfigParent is annotated with @Configuration, it will be created as an additional configuration class, even though it's extended by WebConfigChild. You could exclude WebConfigParent from component scanning.

Try adding something like:

@ComponentScan(excludeFilters = @ComponentScan.Filter(type = FilterType.REGEX, pattern = "*.WebConfigParent"))