[BUG][typescript-angular] UniqueItems and `queryParamObjectFormat=json` are incompatible

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?
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Description

When queryParamObjectFormat=json is set the function addToHttpParamsRecursive does not handle Set types correctly.

https://github.com/snebjorn/openapi-gen-bug/blob/c68a099cdfc29956c7c5c560dc4025722dac5323/output-6.1.0/object-format-json-bug/api/default.service.ts#L62-L75

if (typeof value === "object") {
    httpParams = httpParams.append(key, JSON.stringify(value));
} else if (key != null) {
    httpParams = httpParams.append(key, value);
} else {
    throw Error("key may not be null if value is not object or array");
}

That's because a Set is an object

typeof new Set() // -> 'object'

Now that I think about it an Array is also an object. But it JSON.stringifys better.

JSON.stringify([1,2]) // -> '[1,2]'
JSON.stringify(new Set([1,2])) // -> '{}'

openapi-generator version

6.1.0

OpenAPI declaration file content or url

https://github.com/snebjorn/openapi-gen-bug/blob/master/object-format-json-bug.json

{
  "openapi": "3.0.0",
  "info": {
    "title": "",
    "version": ""
  },
  "paths": {
    "/Foos": {
      "get": {
        "parameters": [
          {
            "name": "$select",
            "in": "query",
            "explode": false,
            "schema": {
              "type": "array",
              "uniqueItems": true,
              "items": {
                "type": "string",
                "enum": ["Foo", "Bar"]
              }
            }
          }
        ],
        "responses": {
          "200": {
            "description": ""
          }
        }
      }
    }
  }
}

Generation Details

additionalProperties:
  queryParamObjectFormat: json

Steps to reproduce

1. Clone https://github.com/snebjorn/openapi-gen-bug
2. Run yarn install
3. Run yarn gen
4. Observe erroneous logic in addToHttpParamsRecursive https://github.com/snebjorn/openapi-gen-bug/blob/c68a099cdfc29956c7c5c560dc4025722dac5323/output-6.1.0/object-format-json-bug/api/default.service.ts#L62

Related issues/PRs

None found

Suggest a fix

Not sure. Seems that whole section needs a long hard look

Clone the linked reproduction, run yarn install and yarn gen, then inspect output-6.1.0/object-format-json-bug/api/default.service.ts around addToHttpParamsRecursive. Trace how uniqueItems arrays become Set values when queryParamObjectFormat=json is enabled. Done means the generated client serializes those query parameters correctly instead of producing an empty JSON object.