Gumdrop\Application::setDestinationLocation PHP Method

    public function setDestinationLocation($destinationLocation)
    {
        $this->destinationLocation = $destinationLocation;
    }

 public function setDestinationFallback()
 {
     if ($this->app->getDestinationLocation() == '') {
         $this->app->setDestinationLocation($this->app->getSourceLocation() . '/_site');
     }
 }