[Feature] Support OpenAPI3 "style" parameters in SDK generators

[ashb]

There is a feature of OpenAPI 3 that lets you change the style of how repeated parameters are specified https://spec.openapis.org/oas/v3.0.3#parameterStyle and https://spec.openapis.org/oas/v3.0.3#style-examples

The particular use case I have is to set explode=false to have CSV parameters rather than multiple query params.

Minimal OpenAPI spec file:

{
  "info": {
    "title": "My API",
    "version": "1.0.0"
  },
  "openapi": "3.0.3",
  "paths": {
    "/test/": {
      "get": {
        "parameters": [
          {
            "in": "query",
            "explode": false,
            "name": "parameter",
            "required": true,
            "schema": {
              "items": {
                "type": "string"
              },
              "type": "array"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "OK"
          }
        }
      }
    }
  }
}

When called with multiple params this should result in ?parameter=a,b,c but it always/only produces ?parameter=a&parameter=b&parameter=c.

I've checked the python and Go SDK generators, and neither handle these style parameters, so I assume this is a universal feature request, though specifically I'm exploring Go, Python and Typescript generators.

[dannysheridan]

@ashb thanks for the issue! I'll pull this forward from our backlog and see where we can slot it in. Will keep you updated here!