Order method1(Map json) { return Order() ..x = json['x'] as List ..y = json['y'] as int; } Order method2(Map json) { return Order() ..x = json['x'] as List? ..y = json['y'] as int; } Order method3(Map json) { return Order() ..x = (json['x'] as List?) ..y = json['y'] as int; } Order method4(Map json) { return Order() ..x = json['x'] as List?; } class Order { List? x; int? y; }