@type t() :: %BexioApiClient.Purchase.BillLineItem{
  amount: float(),
  booking_account_id: integer() | nil,
  id: String.t() | nil,
  position: non_neg_integer(),
  tax_calc: float() | nil,
  tax_id: integer() | nil,
  title: String.t() | nil
}

Line item of a bill in purchase.

Fields:

• :id - id of the line item, nil for new line items in update requests
• :position - position of the line item
• :tax_id - references a tax object, must be nil when the bill is not subject to VAT
• :tax_calc - calculated tax amount, only returned by the API
• :amount - amount of the line item, net or gross depending on the bill's :item_net?
• :booking_account_id - references a booking account object