title: Spring Boot application has about 20 ObjectMappers
body: <p>I'm trying to configure the Jackson <code>ObjectMapper</code> in a Spring Boot application. I've tried various approaches as suggested here and in the documentation (e.g. using a <code>Jackson2ObjectMapperBuilder</code> or <code>Jackson2ObjectMapperBuilderCustomizer</code> <code>@Bean</code>). I want to register a mixin to exclude some fields in the <code>DefaultMessageSourceResolvable</code> class, which should be fairly straightforward.</p>
  
  <p>However, by placing a breakpoint in the <code>ObjectMapper</code> constructor, I've seen that there are about 20 instances being created. Multiple instances of <code>Jackson2ObjectMapperBuilder</code> are created as well.</p>
  
  <p>Creating a bean of the <code>Jackson2ObjectMapperBuilderCustomizer</code> type does not work either; it gets invoked, but the mixin is not registered in the instance which is eventually used for serialization.</p>
  
  <p>Is it normal to have so many instances of these classes? If it is, what might be the reason that my customization efforts fail? If not, what might be wrong and how may it be fixed?</p>