Elgg\Config::set PHP Method

    public function set($name, $value)
    {
        $name = trim($name);
        $this->config->{$name} = $value;
    }

 /**
  * Set up config appropriately on engine boot.
  *
  * @return void
  */
 function init()
 {
     $lastcache = $this->config->get('lastcache');
     if (!defined('UPGRADING') && empty($lastcache)) {
         $this->config->set('lastcache', (int) $this->datalist->get('simplecache_lastupdate'));
     }
 }