type '(dynamic) => dynamic' is not a subtype of type '(String) => Widget' of 'f' code example

Example: type 'List' is not a subtype of type 'List'

snapshot.data.documents.map<Widget>((document) {
  return new ListTile(
    title: new Text(document['name']),
    subtitle: new Text("Class"),
  );
}).toList()