[BUG] [aspnetcore] Object as query parameter not correctly handled

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

Having an object as query parameter the generated csharp-netcore produces a request like this

https://localhost:44301/TestObject?data=class%20TestObject%20%7b%0a%20%20A%3a%201%0a%20%20B%3a%202%0a%7d%0a
Unescaped: https://localhost:44301/TestObject?data=class TestObject { A: 1 B: 2 }

which isn't correctly handled by the aspnetcore server.

The object's properties are always 0.

See Steps to reproduce for more details.

openapi-generator version

Tested with 5.3.0, 5.4.0, 6.0.0-SNAPSHOT

OpenAPI declaration file content or url

openapi: "3.0.0"
info:
  version: 0.1.0
  title: TestObject API
servers:
  - url: http://localhost/
paths:
  /TestObject:
    get:
      operationId: GetTestObject
      tags: 
        - configuration
      parameters:
        - name: data
          in: query
          description: Reads a TestObject
          required: true
          schema:
            $ref: "#/components/schemas/TestObject"        
      responses:
        '200':
          description: TestObject
          content:
            text/plain:
              schema:
                type: boolean
components:
  schemas:
    TestObject:
      type: object
      required:
      - A
      - B
      properties:
        A:
          type: integer
        B:
          type: integer

Generation Details

java -jar ".\openapi-generator-cli-5.4.0.jar" generate -g aspnetcore -o generated\aspnetcore -i .\api.yml
java -jar ".\openapi-generator-cli-5.4.0.jar" generate -g csharp-netcore -o generated\clientnetcore -i .\api.yml

Steps to reproduce

Generate an aspnetcore server + csharp-netcore client with an object as query parameter.

The minimal csharp-netcore client

ConfigurationApi configurationApi = new ConfigurationApi("https://localhost:44301");
configurationApi.GetTestObject(new TestObject(1, 2));

produces a request like this:

https://localhost:44301/TestObject?data=class%20TestObject%20%7b%0a%20%20A%3a%201%0a%20%20B%3a%202%0a%7d%0a
Unescaped: https://localhost:44301/TestObject?data=class TestObject { A: 1 B: 2 }

which isn't correctly handled by the server, both properties are 0:

The Swagger UI produces this request:
https://localhost:44301/TestObject?A=1&B=2
which also cannot be parsed, both properties are 0.

It is possible to fix the Controller for the Swagger UI by removing

(Name = "data") 

public virtual IActionResult GetTestObject([FromQuery][Required()]TestObject data)

This solves the problem for the Swagger UI, but not for the generated client.

What would be the correct URL?
The one from Swagger UI?
https://localhost:44301/TestObject?A=1&B=2

Then it is a client problem.

Related issues/PRs

Maybe related:
https://github.com/OpenAPITools/openapi-generator/issues/10806
https://github.com/OpenAPITools/openapi-generator/issues/10997

Suggest a fix

Start with the api.yml schema and the generated aspnetcore server and csharp-netcore client produced by the two generation commands. Reproduce the request using ConfigurationApi.GetTestObject and compare its query serialization with the Swagger UI request; done means object properties bind correctly on the server and the generated client sends the supported query form.