[GO] Error generating client, response body is consumed and returned as an empty pointer

Description

When generating go code from a swagger json like this:

   "/api/v2/projects/": {
      "get": {
        "description": "~edited",
        "operationId": "Projects_projects_list",
        "parameters": [
          {
            "description": "A page number within the paginated result set.",
            "in": "query",
            "name": "page",
            "required": false,
            "type": "integer"
          },
          {
            "description": "Number of results to return per page.",
            "in": "query",
            "name": "page_size",
            "required": false,
            "type": "integer"
          },
          {
            "description": "A search term.",
            "in": "query",
            "name": "search",
            "required": false,
            "type": "string"
          }
        ],
        "responses": {
          "200": {
            "description": ""
          }
        },
        "summary": " List Projects",
        "tags": [
          "Projects"
        ]
      },
...

the following go code is generated:

func (a *ProjectsApiService) ProjectsProjectsList(ctx context.Context, localVarOptionals *ProjectsApiProjectsProjectsListOpts) (*http.Response, error) {
	var (
		localVarHttpMethod = strings.ToUpper("Get")
		localVarPostBody   interface{}
		localVarFileName   string
		localVarFileBytes  []byte
		
	)

	// create path and map variables
	localVarPath := a.client.cfg.BasePath + "/api/v2/projects/"

	localVarHeaderParams := make(map[string]string)
	localVarQueryParams := url.Values{}
	localVarFormParams := url.Values{}

	if localVarOptionals != nil && localVarOptionals.Page.IsSet() {
		localVarQueryParams.Add("page", parameterToString(localVarOptionals.Page.Value(), ""))
	}
	if localVarOptionals != nil && localVarOptionals.PageSize.IsSet() {
		localVarQueryParams.Add("page_size", parameterToString(localVarOptionals.PageSize.Value(), ""))
	}
	if localVarOptionals != nil && localVarOptionals.Search.IsSet() {
		localVarQueryParams.Add("search", parameterToString(localVarOptionals.Search.Value(), ""))
	}
	// to determine the Content-Type header
	localVarHttpContentTypes := []string{"application/json"}

	// set Content-Type header
	localVarHttpContentType := selectHeaderContentType(localVarHttpContentTypes)
	if localVarHttpContentType != "" {
		localVarHeaderParams["Content-Type"] = localVarHttpContentType
	}

	// to determine the Accept header
	localVarHttpHeaderAccepts := []string{}

	// set Accept header
	localVarHttpHeaderAccept := selectHeaderAccept(localVarHttpHeaderAccepts)
	if localVarHttpHeaderAccept != "" {
		localVarHeaderParams["Accept"] = localVarHttpHeaderAccept
	}
	r, err := a.client.prepareRequest(ctx, localVarPath, localVarHttpMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, localVarFileName, localVarFileBytes)
	if err != nil {
		return nil, err
	}

	localVarHttpResponse, err := a.client.callAPI(r)
	if err != nil || localVarHttpResponse == nil {
		return localVarHttpResponse, err
	}

	localVarBody, err := ioutil.ReadAll(localVarHttpResponse.Body)  //THE PROBLEM IS HERE
	localVarHttpResponse.Body.Close()
	if err != nil {
		return localVarHttpResponse, err
	}


	if localVarHttpResponse.StatusCode >= 300 {
		newErr := GenericSwaggerError{
			body: localVarBody,
			error: localVarHttpResponse.Status,
		}
		
		return localVarHttpResponse, newErr
	}

	return localVarHttpResponse, nil  //AND HERE
}

The problem in this function is that this line localVarBody, err := ioutil.ReadAll(localVarHttpResponse.Body) read the body of the response pointer and leave the localVarHttpResponse.Body empty. As a consequence the return localVarHttpResponse, nil returns the pointer to the response with the empty body.
This seems the case for any resource generated.

Swagger-codegen version

3.0.20

Swagger declaration file content or url

https://github.com/Roviluca/awx-go-autogenerated/blob/main/swagger.json

Command line used for generation

swagger-codegen generate -i ./swagger.json -l go -o ./test-codegen

Suggest a fix/enhancement

You can consume the content of the body only if needed by the return by moving the ReadAll inside the if checking for the response code >300.

if localVarHttpResponse.StatusCode >= 300 {
		localVarBody, err := ioutil.ReadAll(localVarHttpResponse.Body)
		localVarHttpResponse.Body.Close()
		if err != nil {
			return localVarHttpResponse, err
		}
		newErr := GenericSwaggerError{
			body: localVarBody,
			error: localVarHttpResponse.Status,
		}
		return localVarHttpResponse, newErr
	}

	return localVarHttpResponse, nil```

Start with the Go client generation path invoked by swagger-codegen generate -i ./swagger.json -l go -o ./test-codegen, then trace the generated ProjectsProjectsList response handling and its callAPI entry point. Reproduce the behavior using the linked Swagger declaration and verify that successful responses retain a readable body while error responses still expose their body and status.