[BUG] [Dart-dio] AnyOf not processed correctly in query params

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 Dart code with a schema that contains anyOf in the query params, the generated classes don't compile because of missing types in OpenAPI Generator CLI 6.0.0 (Snapshot 2022.05.13).

openapi-generator version

openapi-generator-cli-6.0.0-20220513.065916-158

OpenAPI declaration file content or url

"/my-endpoint": {
      "get": {
        "operationId": "list",
        "tags": ["My Endpoint"],
        "parameters": [
          {
            "in": "query",
            "name": "parentId",
            "required": false,
            "schema": {
              "anyOf": [
                {
                  "type": "array",
                  "items": { "format": "uuid", "type": "string" }
                },
                { "format": "uuid", "type": "string" },
                { "type": "null" }
        ]}}],
}

Generation Details

The output that comes out is the following:

Future<Response<MyEndpointResponse>> list({ 
    AnyOfarrayUUIDnull? parentId,
    ...
    }) {}

The type AnyOfarrayUUIDnull? doesn't actually exist in the generated code, leading to code that doesn't compile.

Steps to reproduce

1. Create a schema with anyOf in the query params
2. Run java -cp openapi-generator-cli-6.0.0-20220513.065916-158.jar org.openapitools.codegen.OpenAPIGenerator generate -i <input_file.json> -g dart-io
3. The resulting API file will have the incorrectly generated types in it

Related issues/PRs

I previously had this issue with bodies and enums as well. This was fixed in https://github.com/OpenAPITools/openapi-generator/issues/10930

Suggest a fix

Reproduce the issue with the OpenAPIGenerator entry point org.openapitools.codegen.OpenAPIGenerator and the documented dart-io command using the supplied schema. Inspect the Dart generator path responsible for query parameter types. Done means the generated API file no longer references the missing AnyOfarrayUUIDnull type and compiles successfully.