Custom GET service without path arg results in could not find controller

I'm not sure if this is a bug or not, but it seems like one. I have a custom service that uses GET with retrieve method, REST server, and only has params as args for the service. The result of calling the service is controller not found. After going through RESTServer.inc where resolveController is located, there is the following logic for determining the $class and $operation:

// 'retrieve' method.
// First path element should be not empty.
if ($method == 'GET' && isset($resource['operations']['retrieve']) && $this->checkNumberOfArguments($pc, $resource['operations']['retrieve']) && !empty($path[0]) && $pc >= 1) {
  $class = 'operations';
  $operation = 'retrieve';
}

This if condition fails and $class stays FALSE. When the method returns, $class is still FALSE and results in $controller = FALSE and eventually controller not found error. The if statement is TRUE for all parts except the call to checkNumberOfArguments. So I looked into checkNumberOfArguments for my service call that isn't working, and also with a service call that is working to see what was different. Here is checkNumberOfArguments function for reference:

  /**
   * Count possible numbers of 'path' arguments of the method.
   */
  private function checkNumberOfArguments($args_number, $resource_operation, $required_args = 0) {
    $not_required_args = 0;

    if (isset($resource_operation['args'])) {
      foreach ($resource_operation['args'] as $argument) {
        if (is_array($argument['source']) && isset($argument['source']['path'])) {
          if (!empty($argument['optional'])) {
            $not_required_args++;
          }
          else {
            $required_args++;
          }
        }
      }
    }

    return $args_number >= $required_args && $args_number <= $required_args + $not_required_args;
  }

What I have found is that when the service only defines param arguments, the checkNumberOfArguments function will always return FALSE when called without the 3rd parameter for $required_args. Since $required_args = 0, and after the loop finishes in checkNumberOfArguments, $not_required_args = 0, then the conditional return statement always evaluates to FALSE.

So, I can fix my service call problem by inserting a dummy path argument which satisfies checkNumberOfArguments, but I'm wondering if that is the right solution. Is it ok for a service to only have param-style args or should every service define at least one path element? If that's the case, then I just need to update the service, and remember that for the future. If that's not the case, then I guess the logic needs to be adjusted in checkNumberOfArguments or possibly in resolveController.

Hopefully I've provided enough information. If not, ask for clarification, and I'll provide it.