Realizando requisição em Flutter

flutter_futurebuilder.dart

FutureBuilder<List<SuperHero>>(
          future: futureSuperHeros,
          builder: (context, snapshot) {
            if (snapshot.hasData) {
              return buildList(snapshot.requireData);
            } else if (snapshot.hasError) {
              return Text('${snapshot.error}');
            }
            return const CircularProgressIndicator();
          },
        ),

flutter_repository.dart

class SuperHeroApi {
  Future<List<SuperHero>> fetchAllSuperHero() async {
    final response = await http
        .get(Uri.parse('https://olamundo.com'));
    if (response.statusCode == 200) {

      Iterable l = jsonDecode(response.body);
      return List<SuperHero>.from(l.map((model)=> SuperHero.fromJson(model)));

      // return SuperHero.fromJson(jsonDecode(response.body));
    } else {
      throw Exception('Failed to load super hero');
    }
  }
}