toJson method
Implementation
Map<String, dynamic> toJson() {
  final Map<String, dynamic> data = new Map<String, dynamic>();
  data['id'] = this.id;
  data['title'] = this.title;
  data['method_id'] = this.methodId;
  data['cost'] = this.cost;
  if (minimumOrderAmount != null) {
    data['minimum_order_amount'] = this.minimumOrderAmount;
  }
  return data;
}