protected function startProvidersPlugin($app)
    {
        switch ($this->registerProvidersOn) {
            case 'register':
                $this->onRegister('providers', function () {
                    $this->handleProviders();
                });
                break;
            case 'booting':
                $this->app->booting(function () {
                    $this->handleProviders();
                });
                break;
            case 'boot':
                $this->onBoot('providers', function () {
                    $this->handleProviders();
                });
                break;
            case 'booted':
                $this->app->booted(function () {
                    $this->handleProviders();
                });
                break;
            default:
                throw new \LogicException('registerProvidersOn not valid');
                break;
        }
    }