allOf:
  - $ref: ./InventoryItemDTO.yaml
  - type: object
    properties:
      location_levels:
        type: array
        description: The inventory's location levels.
        items:
          allOf:
            - $ref: ./InventoryItemDTO.yaml
            - type: object
              required:
                - available_quantity
              properties:
                available_quantity:
                  description: The available quantity in the inventory location.
                  type: number