Magento2 Swagger generated php client - list parameterization broken

I've generated a PHP client library for Magento2, against their public schema, using swagger-codegen. I'm able to connect to Magento and just trying some methods to see how usable the generated client is. It seems like I'm either missing something or maybe the swagger spec published by Magento is not quite there yet.

In particular, invoking the various list operations seems to be marginalized by design, and broken by nature in the generated swagger client. Take for example the operation to list products, /V1/products. Swagger UI indicates this can be parameterized with GET parameters (and in fact seems you must - when I try calling it with no parameters Magento returns an HTTP 400). Here's the sample generated code from the Markdown Swagger generated along with the client library

try { 
    $result = $api_instance->catalogProductRepositoryV1GetListGet(
        $search_criteria_filter_groups_filters_field, 
        $search_criteria_filter_groups_filters_value, 
        $search_criteria_filter_groups_filters_condition_type, 
        $search_criteria_sort_orders_field,  
        $search_criteria_sort_orders_direction, $search_criteria_page_size, 
        $search_criteria_current_page);
    print_r($result);
} catch (Exception $e) {
    echo
        'Exception when calling CatalogProductRepositoryVApi->catalogProductRepositoryV1GetListGet: ',
        $e->getMessage(), "\n";
}

The first thing I notice is that these parameters only allow a single entry for each field, when the API actually allows you to define multiple filter_groups, multiple filters per filter_group etc. This great blog post helped me understand how the API is supposed to work.

Stepping back though, and supposing a limit of one filter_group and one filter for that group are acceptable and just trying to use the generated client on faith, I tried to put together a simple call

// Fetch all products with a contrived like query
$oMageClient = new Swagger\Client\Api\CatalogProductRepositoryVApi($oApiClient);
$result      = $oMageClient->catalogProductRepositoryV1GetListGet('name', '%', 'like');

Magento complains with an HTTP 400, and it's because of the generated client's request params:

searchCriteria[filterGroups][][filters][][field]=name&searchCriteria[filterGroups][][filters][][value]=%&searchCriteria[filterGroups][][filters][][conditionType]=like

What it's done is broken up the parameters into different filter_groups... Sure enough when I look at the generated Swagger\Client\Api\CatalogProductRepositoryVApi:: catalogProductRepositoryV1GetListGetWithHttpInfo method I find the culprit where the query params are set. By changing

// query params
if ($search_criteria_filter_groups_filters_field !== null) {
    $queryParams['searchCriteria[filterGroups][][filters][][field]'] = $this->apiClient->getSerializer()->toQueryValue($search_criteria_filter_groups_filters_field);
}// query params
if ($search_criteria_filter_groups_filters_value !== null) {
    $queryParams['searchCriteria[filterGroups][][filters][][value]'] = $this->apiClient->getSerializer()->toQueryValue($search_criteria_filter_groups_filters_value);
}// query params
if ($search_criteria_filter_groups_filters_condition_type !== null) {
    $queryParams['searchCriteria[filterGroups][][filters][][conditionType]'] = $this->apiClient->getSerializer()->toQueryValue($search_criteria_filter_groups_filters_condition_type);
}

to

// query params
if ($search_criteria_filter_groups_filters_field !== null) {
    $queryParams['searchCriteria[filterGroups][0][filters][0][field]'] = $this->apiClient->getSerializer()->toQueryValue($search_criteria_filter_groups_filters_field);
}// query params
if ($search_criteria_filter_groups_filters_value !== null) {
    $queryParams['searchCriteria[filterGroups][0][filters][0][value]'] = $this->apiClient->getSerializer()->toQueryValue($search_criteria_filter_groups_filters_value);
}// query params
if ($search_criteria_filter_groups_filters_condition_type !== null) {
    $queryParams['searchCriteria[filterGroups][0][filters][0][conditionType]'] = $this->apiClient->getSerializer()->toQueryValue($search_criteria_filter_groups_filters_condition_type);
}

I'm able to get a response back from Magento. So I have a couple of questions

So is there an issue with the JSON Magento is publishing causing the generated Swagger code to be buggy? Or is there some other step I've messed up in generating the client?

It feels like something's not right, because if you look at the blog article and the generated Swagger documentation, Swagger is suggesting the filter_groups parameter is a string, when really it should be an array of objects.

Start with the Magento schema linked in the issue and the generated PHP CatalogProductRepositoryV1GetListGetWithHttpInfo method, comparing its filter_groups parameters with the query string it produces. Reproduce the /V1/products request and determine whether the schema or generator causes the missing array indexes; done means the generated client emits parameters Magento accepts for list operations.