我有这段代码来调用API;我如何向其中添加授权和内容类型头？

final url = Uri.parse('https://api.collectapi.com/economy/hisseSenedi');
  var counter;
  var hisseResult;
  Future callHisse() async {
    try{
      final response = await http.get(url);

      if(response.statusCode == 200){
        var result = hisselistFromJson(response.body);
        if(mounted);
        setState(() {
          counter = result.data.length;
          hisseResult = result;
        });
        return result;
      } else {
        print(response.statusCode);
      }
    } catch(e) {
      print(e.toString());
    }

  }

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