Configuring ObjectMapper in Spring

Question

my goal is to configure the objectMapper in the way that it only serialises element which are annotated with @JsonProperty.

In order to do

Answer 1

SOLUTION 1

First working solution (tested) useful especially when using @EnableWebMvc:

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private ObjectMapper objectMapper;// created elsewhere
    @Override
    public void extendMessageConverters(List> converters) {
        // this won't add a 2nd MappingJackson2HttpMessageConverter 
        // as the SOLUTION 2 is doing but also might seem complicated
        converters.stream().filter(c -> c instanceof MappingJackson2HttpMessageConverter).forEach(c -> {
            // check default included objectMapper._registeredModuleTypes,
            // e.g. Jdk8Module, JavaTimeModule when creating the ObjectMapper
            // without Jackson2ObjectMapperBuilder
            ((MappingJackson2HttpMessageConverter) c).setObjectMapper(this.objectMapper);
        });
    }

SOLUTION 2

Of course the common approach below works too (also working with @EnableWebMvc):

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private ObjectMapper objectMapper;// created elsewhere
    @Override
    public void extendMessageConverters(List> converters) {
        // this will add a 2nd MappingJackson2HttpMessageConverter 
        // (additional to the default one) but will work and you 
        // won't lose the default converters as you'll do when overwriting
        // configureMessageConverters(List> converters)
        // 
        // you still have to check default included
        // objectMapper._registeredModuleTypes, e.g.
        // Jdk8Module, JavaTimeModule when creating the ObjectMapper
        // without Jackson2ObjectMapperBuilder
        converters.add(new MappingJackson2HttpMessageConverter(this.objectMapper));
    }

Why @EnableWebMvc usage is a problem?

@EnableWebMvc is using DelegatingWebMvcConfiguration which extends WebMvcConfigurationSupport which does this:

if (jackson2Present) {
    Jackson2ObjectMapperBuilder builder = Jackson2ObjectMapperBuilder.json();
    if (this.applicationContext != null) {
        builder.applicationContext(this.applicationContext);
    }
    messageConverters.add(new MappingJackson2HttpMessageConverter(builder.build()));
}

which means that there's no way of injecting your own ObjectMapper with the purpose of preparing it to be used for creating the default MappingJackson2HttpMessageConverter when using @EnableWebMvc.