Short answer is the presence or absence of a field can drive us to different paths in the code base. That can lead to code littered with !! and @JsonIgnorePrope

Short answer is the presence or absence of a field can drive us to different paths in the code base. That can lead to code littered with !! and @JsonIgnoreProperties(ignoreUnknown=true), or multiple intermediary data classes, or similar solutions. For much of our problem space, an extra val or two and some well placed ifs get us out of it.