encoder method
The mapping method to encode value to a serializable value.
Implementation
@override
Object? encoder(T value, EncodingContext context) {
  if (superHook != null) {
    var result = superHook!.beforeEncode(value);
    if (result is! T) {
      return superHook!.afterEncode(result);
    }
    value = result;
  }
  var result = super.encoder(value, context);
  if (superHook != null) {
    result = superHook!.afterEncode(result);
  }
  return result;
}