toJson method Null safety

Implementation

Map<String, dynamic> toJson() {
  final Map<String, dynamic> data = <String, dynamic>{};
  data['hairLine'] = _hairline;
  data['thin'] = _thin;
  data['light'] = _light;
  data['normal'] = _normal;
  data['medium'] = _medium;
  data['semiBold'] = _semibold;
  data['bold'] = _bold;
  data['extraBold'] = _extrabold;
  data['black'] = _black;
  data['extraBlack'] = _extraBlack;
  return data;
}