ObjectMapper in RestClient not picking up configuration properties

Question

In my Spring Boot service, I'm using RestClient to perform REST calls. I want to ignore null values in request bodies so I set up

spring:
  jackson:
    default-property-inclusion: "non_null"

in my application.yml. However, the config is not respected for some reason in the RestClient's ObjectMapper. On the other hand, when I inject the Spring auto-configured ObjectMapper into my test class (annotated with @SpringBootTest) I see the mapper configured as expected. What could be the reason for RestClient picking up a different ObjectMapper than the one configured by Spring Boot?

Couple of notes:

• I'm not configuring ObjectMapper in any other way than via application.yml
• I'm doing RestClient.create() to set up the RestClient
• I don't use @EnableWebMvc (the usual suspect in similar SO questions)

Answer 1

You need to, at least, use RestClient.create(restTemplate). Your RestTemplate needs to be configured with the ObjectMapper you need.

When you use RestClient.create() it has no way of picking up spring-configured mapper, how could it? It's regular java object creation.

There are some other options, for example:

RestClient.builder()
  .messageConverters(in -> {
    MappingJackson2HttpMessageConverter jacksonConverter = new MappingJackson2HttpMessageConverter();
    messageConverter.setPrettyPrint(false);
    messageConverter.setObjectMapper(objectMapper);
    in.add(jacksonConverter);
  })
.build();