app/Http/Controllers/Auth/AuthController.php
protected function validateRegistration(Request $request, $withSubscription = false)
    {
        if (Spark::$validateProfileUpdatesWith) {
            $this->callCustomValidator(
                Spark::$validateProfileUpdatesWith, $request, [$withSubscription]
            );
        } else {
            $this->validateDefaultRegistration($request, $withSubscription);
        }
    }
protected function validateRegistration(Request $request, $withSubscription = false)
    {
        if (Spark::$validateProfileUpdatesWith) {
            $this->callCustomValidator(
                Spark::$validateProfileUpdatesWith, $request, [$withSubscription]
            );
        } else {
            $this->validateDefaultRegistration($request, $withSubscription);
        }
    }
Validate the new registration.

@param  \Illuminate\Http\Request  $request
@param  bool  $withSubscription
@return void