public function build()
{
parent::build();
//set the upload url depending on the type of config this is
$url = $this->validator->getUrlInstance();
$route = $this->config->getType() === 'settings' ? 'admin_settings_file_upload' : 'admin_file_upload';
//set the upload url to the proper route
$this->suppliedOptions['upload_url'] = $url->route($route, array($this->config->getOption('name'), $this->suppliedOptions['field_name']));
}