code: @JsonAnySetter
      protected void handleUnknown(String key, Object value) {
          StringBuilder unknown = new StringBuilder(this.getClass().getSimpleName());
          unknown.append(": Unknown property='").append(key);
          unknown.append("' value='").append(value).append("'");
  
          LOG.trace(unknown.toString());
      }
docs: Handle unknown properties and print a message
  
  @param key
  @param value