Versioning doesn't work with custom resources

I think this is a bug, but I'm not sure.

I have a working API based on the services module for one year now. And today I started working on a second version.
I browsed through the code to find out how I should build my resource files in order to support different versions.

At the moment it works but I had to "hack" the services module.
Look at this function:

/**
 * Returns currently set api version for an endpoint resource method.
 *
 * @param $endpoint
 *   A fully loadded endpoint.
 * @param $resource
 *   A resource name.
 * @param $method
 *   A method name.
 * @return
 *   an array with the major and minor api versions
 */
function services_get_resource_api_version($endpoint, $resource, $method) {
  if (isset($endpoint->resources[$resource]) ) {
    $class_info = services_operation_class_info();
    foreach ($class_info as $class_name => $class) {
      if (!empty($resource[$class_name])) {
        if (isset($endpoint->resources[$resource][$class_name][$method]['settings']['services']['resource_api_version'])) {
          if($version = _services_version_header_options()) {
            $split = explode('.', $version);
          } else {
            $split = explode('.', $endpoint->resources[$resource][$class_name][$method]['settings']['services']['resource_api_version']);
          }
          return array(
            'major' => $split[0],
            'minor' => $split[1],
          );
        }
      }
    }
  }
}

It defines in it's docblock that "@param $resource" is a String, the name of the resource.
In my case it is "frontpage".

A few lines beneath that you'll see the following line

if (!empty($resource[$class_name])) {

I wonder how this can work as

1. $resource is a string an not an array
2. $classname can only be one of these: 'operations', 'actions', 'relationships', 'targeted_actions'

After removing that line everything seems to work, but I'm not sure if it causes any problems I can't think off.