InvoiceItem:
      type: object
      properties:
        quantity:
          type: integer
          example: 1
          description: 'The quantity of the product offered for this line item'
        cost:
          type: number
          format: float
          example: 10.00
          description: 'The cost of the product offered for this line item'
        product_key:
          type: string
          example: 'Product key'
          description: 'The product key of the product offered for this line item (Referred to as Product in the product tab)'
        product_cost:
          type: number
          format: float
          example: 10.00
          description: 'The cost of the product offered for this line item (Referred to as Cost in the product tab)'
        notes:
          type: string
          example: 'Item notes'
          description: 'The notes/description for the product offered for this line item'
        discount:
          type: number
          format: float
          example: 5.00
          description: 'The discount applied to the product offered for this line item'
        is_amount_discount:
          type: boolean
          example: false
          description: 'Indicates whether the discount applied to the product offered for this line item is a fixed amount or a percentage'
        tax_name1:
          type: string
          example: 'GST'
          description: 'The name of the first tax applied to the product offered for this line item'
        tax_rate1:
          type: number
          format: float
          example: 10.00
          description: 'The rate of the first tax applied to the product offered for this line item'
        tax_name2:
          type: string
          example: 'VAT'
          description: 'The name of the second tax applied to the product offered for this line item'
        tax_rate2:
          type: number
          format: float
          example: 5.00
          description: 'The rate of the second tax applied to the product offered for this line item'
        tax_name3:
          type: string
          example: 'CA Sales Tax'
          description: 'The name of the third tax applied to the product offered for this line item'
        tax_rate3:
          type: number
          format: float
          example: 3.00
          description: 'The rate of the third tax applied to the product offered for this line item'
        sort_id:
          type: string
          example: '0'
          description: 'Deprecated'
          deprecated: true
        line_total:
          type: number
          format: float
          example: 10.00
          description: 'The total amount of the product offered for this line item'
          readOnly: true
        gross_line_total:
          type: number
          format: float
          example: 15.00
          description: 'The total amount of the product offered for this line item before discounts'
          readOnly: true
        tax_amount:
          type: number
          format: float
          example: 1.00
          description: 'The total amount of tax applied to the product offered for this line item'
          readOnly: true
        date:
          type: string
          format: date-time
          example: '2023-03-19T00:00:00Z'
          description: 'Deprecated'
          deprecated: true
        custom_value1:
          type: string
          example: 'Custom value 1'
          description: 'The first custom value of the product offered for this line item'
        custom_value2:
          type: string
          example: 'Custom value 2'
          description: 'The second custom value of the product offered for this line item'
        custom_value3:
          type: string
          example: 'Custom value 3'
          description: 'The third custom value of the product offered for this line item'
        custom_value4:
          type: string
          example: 'Custom value 4'
          description: 'The fourth custom value of the product offered for this line item'
        type_id:
          type: string
          example: '1'
          description: '1 = product, 2 = service, 3 unpaid gateway fee, 4 paid gateway fee, 5 late fee, 6 expense'
          default: '1'
        tax_id:
          type: string
          example: '1'
          default: '1'
          description: 'The tax ID of the product: 1 product, 2 service, 3 digital, 4 shipping, 5 exempt, 5 reduced tax, 7 override, 8 zero rate, 9 reverse tax'