@type t() :: %ExPipedrive.DealProduct{
  add_time: (DateTime.t() | NaiveDateTime.t()) | nil,
  billing_frequency: String.t() | nil,
  billing_frequency_cycles: integer() | nil,
  billing_start_date: Date.t() | nil,
  comments: String.t() | nil,
  currency: String.t() | nil,
  deal_id: pos_integer() | nil,
  discount: number() | nil,
  discount_type: String.t() | nil,
  id: pos_integer() | nil,
  is_enabled: boolean(),
  item_price: number() | nil,
  name: String.t() | nil,
  order_nr: integer() | nil,
  original_object: map() | nil,
  product_id: pos_integer() | nil,
  product_variation_id: pos_integer() | nil,
  quantity: number() | nil,
  sum: number() | nil,
  tax: number() | nil,
  tax_method: String.t() | nil,
  update_time: (DateTime.t() | NaiveDateTime.t()) | nil
}