isVirtual method
When true the content can be received through getVirtualFileReceiver.
On macOS and Windows if isVirtual is true the content can only be
received through getVirtualFileReceiver - getDataForFormat will return
null.
Implementation
Future<bool> isVirtual(String format) async {
return (await _getItemInfo()).virtualReceivers.any(
(element) => element.format == format,
);
}