[BUG] [csharp-netcore] Parameter of type Enum will not use EnumMember attribute but rather serialise Enum.Tostring()

Created by: jafin

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?
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What's the actual output vs expected output?

Description

A Get query that takes an enum string type as a parameter, is not serializing into the correct value. Instead, it is being serialized to the Enum name not the EnumMember value

In the below example, PetStatusFilter will return title case Available or Pending or Sold. whereas it should return available or pending or sold

/pet/findByStatusWithFilter:
    get:
      tags:
        - pet
      summary: Finds Pets by status
      description: Multiple status values can be provided with comma separated strings
      operationId: findPetsByStatusWithFilter
      parameters:
        - name: status
          in: query
          description: Status values that need to be considered for filter
          required: true
          schema:
            type: array
            items:
              $ref: '#/components/schemas/PetStatusFilter'
    PetStatusFilter:
      type: string
      enum:
        - available
        - pending
        - sold

openapi-generator version

5.4
main

Generation Details

The method in ClientUtils , ParameterToString does not check if obj is an Enum, and will default return obj.ToString(). Instead, it should be looking at the Enum's EnumMember attribute fo the value to return.

Steps to reproduce

Run generator ./bin/generate-sample.sh ./bin/configs/csharp with a modified version of the petstore.yaml including the above changes.

Related issues/PRs

None found