multiple path parameters and strings in same path segment conform to OAS 3.0.x ?

[amolari]

I'm battling with a (api) security vendor about the conformity to OAS 3.0.x of such specfile snippet:

paths:
  "/MaterialStocks(Material='{Material}',Warehouse='{Warehouse}')":
    parameters:
      - name: Material
        in: path
        required: true
        description: "Article Number  \nAlphanumeric key uniquely identifying the material."
        schema:
          type: string
          maxLength: 18
      - name: Warehouse
        in: path
        required: true
        description: "Warehouse Number / Warehouse Complex  \nNumber that identifies a complex, physical warehouse structure within the Warehouse Management system.  \nAll activities within a warehouse, for example, goods movements and physical inventory, are assigned to a specific warehouse number. The physical warehouse where these activities take place is identified by the warehouse number."
        schema:
          type: string
          maxLength: 3
    get:
      summary: Get entity from MaterialStocks by key
      description: Reads material ID and base unit of measure for a specific material
      operationId: getMaterialStocksByKey
      tags:
        - Material Stock
      parameters:
        - name: $select
          in: query
          description: "Select properties to be returned, see [Select](https://help.sap.com/doc/5890d27be418427993fafa6722cdc03b/Cloud/en-US/OdataV2.pdf#page=68)"
          explode: false
          schema:
            type: array
            uniqueItems: true
            items:
              type: string
              enum:
                - Material
                - Warehouse
                - MaterialBaseUnit
                - to_WhseMatlStks
        - name: $expand
          in: query
          description: "Expand related entities, see [Expand](https://help.sap.com/doc/5890d27be418427993fafa6722cdc03b/Cloud/en-US/OdataV2.pdf#page=63)"
          explode: false
          schema:
            type: array
            uniqueItems: true
            items:
              type: string
              enum:
                - to_WhseMatlStks
      responses:
        "200":
          description: Retrieved entity
          content:
            application/json:
              schema:
                title: MaterialStock
                type: object
                properties:
                  d:
                    $ref: "#/components/schemas/ZAPI_WM_MATERIAL_STOCK_SRV.MaterialStock"
        4XX:
          $ref: "#/components/responses/error"
        5XX:
          $ref: "#/components/responses/error"

That security vendor tells me that those path parameters definitions ( "/MaterialStocks(Material='{Material}',Warehouse='{Warehouse}')") are not conform and therefor their product cannot interpret it correctly.
It's true that in examples found on swagger.io and other places around, the positional parameter is the path-segment such as in "/MaterialStocks/{Material}/{Warehouse}"

On the other hand, it seems that my spec file snippet is conform to RFC6570. I've found also a couple of examples of such specfile such as here

So my question would be basically: is that snippet conform to OAS 3.0.x or not?