class FoodOrder private constructor(
  val bread: String?,
  val condiments: String?,
  val meat: String?,
  val fish: String?) {
 
    data class Builder(
      var bread: String? = null,
      var condiments: String? = null,
      var meat: String? = null,
      var fish: String? = null) {
 
        fun bread(bread: String) = apply { this.bread = bread }
        fun condiments(condiments: String) = apply { this.condiments = condiments }
        fun meat(meat: String) = apply { this.meat = meat }
        fun fish(fish: String) = apply { this.fish = fish }
        fun build() = FoodOrder(bread, condiments, meat, fish)
    }
}