update method
Implementation
void update(Map<String, dynamic> map) {
leftThumbX = map['thumbs'][0];
leftThumbY = map['thumbs'][1];
rightThumbX = map['thumbs'][2];
rightThumbY = map['thumbs'][3];
leftTrigger = map['triggers'][0];
rightTrigger = map['triggers'][1];
buttons = List.generate((map['buttons'] as List).length,
(index) => GamepadButton.values[map['buttons'][index] as int]);
}