Spring 4 & Jackson 2: ObjectMapper Configuration Not Used For Some Classes

I'm attempting to configure my MVC application's ObjectMapper via code. The issue I'm running into is that it seems to be respecting the configuration when serializing some classes, but not others. In my specific case the class where the ObjectMapper seems to not be used is a Hibernate entity.

Here's a simplified version of the config:

@Configuration
@EnableWebMvc
public class WebMvcDefaultObjectMapperConfigurerAdapter extends WebMvcConfigurerAdapter {

    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        for (HttpMessageConverter<?> httpConverter : converters) {
            if (httpConverter instanceof MappingJackson2HttpMessageConverter) {
                ((MappingJackson2HttpMessageConverter) httpConverter).setObjectMapper(configureMapper());
            }
        }
    }

    @Primary
    @Bean
    public ObjectMapper defaultMapper() {
        return configureMapper();
    }

    private ObjectMapper configureMapper() {
        ObjectMapper mapper = new ObjectMapper();

        PropertyFilter filter = new SimpleBeanPropertyFilter() {...};
        FilterProvider filters = new SimpleFilterProvider().addFilter("myFilter", filter);

        mapper.configure(SerializationFeature.INDENT_OUTPUT, true);
        mapper.setFilterProvider(filters);
        
        return mapper;
    }
}

The exact error I'm running in to is that I have a specific class configured to use a filter (myFilter) but when it gets serialized it throws a JsonMappingException saying "Can not resolve PropertyFilter with id 'myFilter'; no FilterProvider configured...". That would make me think that my configuration is "in the wrong place" and Spring isn't picking it up.

However, I have evidence to the contrary. When an error occurs, my API returns a JSON error message and if I change the value of the INDENT_OUTPUT serialization feature in the above configuration code, it's reflected in that error message (i.e. the error will be pretty printed or not). So it's working for at least some classes.

Does anyone know what can cause a class to somehow be serialized using some other mapper?

Other notes/things I've tried:

• Adding/removing the @EnableWebMvc from the configuration class makes no difference. It fails with the same error either way.
• I've tried configuring the mapper via just about every avenue, i.e. a MappingJackson2HttpMessageConverter bean, HttpMessageConverters bean, Jackson2ObjectMapperBuilder bean, plain old ObjectMapper bean. It's the same error no matter what.
• I've also tried a RestTemplate bean, although I'm not sure I'm actually using that anywhere.

After much debugging, some other strange behavior lead me to the solution.

It turned out that for a different API call, the same hibernate entity would be serialized no problem. The reason for this was because that endpoint function looked like this:

public @ResponseBody List<MyEntity> listEntity() {
    List<MyEntity> entities = ...;
    return entities;
}

But the erroring endpoint looked like this:

public String getEntities(Model model) {
    List<MyEntity> entities = ...;
    model.addAttribute("success", Boolean.TRUE);
    model.addAttribute("entities", entities);
    
    return "jsonTemplate";
}

The difference is that the erroring endpoint was using the jsonTemplate view while the non-erroring one was not. It turns out that in my definition of this view, I wasn't configuring it to use my custom ObjectMapper. Updating it to do so fixed the problem.

The Final Solution

@Bean
public View jsonTemplate() {
    MappingJackson2JsonView view = new MappingJackson2JsonView();
    ObjectMapper myMapper = configureMapper();
    view.setObjectMapper(myMapper);
    return view;
}