whatsNext method
Returns the actual or preferred DecodingType of the encoded data.
Self-describing formats may return a DecodingType that indicates the type of the encoded data, or the preferred way of decoding it.
Non-self-describing formats may only return DecodingType.unknown for all types. In this case, the Decodable implementation must try the appropriate decoding method based on the expected type.
Implementation
@override
DecodingType whatsNext() {
final key = keys.current;
return decoder.whatsNext(key is String ? key : '', id: key is int ? key : null);
}