code: private Model doModel(Type type, Model model) {
      Map<String, Property> properties = model.getProperties();
      if (properties != null) {
        BeanDescription desc = Json.mapper().getSerializationConfig()
            .introspect(Json.mapper().constructType(type));
        for (BeanPropertyDefinition beanProperty : desc.findProperties()) {
          Property property = properties.get(beanProperty.getName());
          if (property != null) {
            property.setRequired(beanProperty.isRequired());
          }
        }
      }
      return model;
    }
docs: Mostly for kotlin null safe operator and immutable properties.
  
  @param type Target type.
  @param model Model.
  @return Input model.