title: Handling Unknown JSON Properties with Jackson
body: <p>For deserializing json with unknown field into an object there's @JsonAnySetter.</p>
  
  <p>But what if I read such json into my object, modify some known fields and write it back to json?
  The unknown properties will be lost.</p>
  
  <p>How do I handle such cases? Is it possible to map an object or do I have to read the data into a JsonNode or Map?</p>