decoder method
The mapping method to decode value to an instance of this mappers type.
Implementation
@override
T decoder(Object? value, DecodingContext context) {
  if (superHook != null && !context.inherited) {
    value = superHook!.beforeDecode(value);
    if (value is T) {
      return superHook!.afterDecode(value) as T;
    }
  }
  var result = super.decoder(value, context);
  if (superHook != null && !context.inherited) {
    result = superHook!.afterDecode(result) as T;
  }
  return result;
}