[BUG][csharp-netcore] Bug generating Array of Array with $ref

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

When generating a object with an array of array member the generated code is List<List>.
This does not compile because of this error:
error CS0305: Using the generic type 'List<T>' requires 1 type arguments

Note that if I don't use $ref (the manualPairStream) the generated code works as it's List<List<int>>

openapi-generator version

6.0.0-SNAPSHOT

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: List of list
  version: v1
paths: {}
components:
  schemas:
    MyClass:
      type: object
      properties:
        manualPairStream:
          type: array
          items:
            type: array
            items:
              type: integer
        pairStream:
          $ref: '#/components/schemas/PairStream'
        pair:
          $ref: '#/components/schemas/Pair'
    PairStream:
      type: array
      items:
        $ref: '#/components/schemas/Pair'
    Pair:
      type: array
      items:
        type: integer

Generation Details

podman run --rm -v ${PWD}:/local docker.io/openapitools/openapi-generator-cli generate -i /local/swagger.yaml -g csharp-netcore -o /local/bugExample

Steps to reproduce

Generate the client with the previous command and run dotnet build in the openapi-bug/bugExample/src/Org.OpenAPITools folder

Start with the supplied OpenAPI declaration and generate the csharp-netcore client using the documented Podman command. Run dotnet build in openapi-bug/bugExample/src/Org.OpenAPITools and inspect the generated PairStream and Pair models; done means the referenced array-of-array property compiles with the expected nested list type.