protected function addGlobalForward(ActionForward $forward, $alias = null) {
        if ($this->configured) throw new IllegalStateException('Configuration is frozen');

        $name = is_null($alias) ? $forward->getName() : $alias;

        if (isset($this->globalForwards[$name])) throw new StrutsConfigException('Non-unique name detected for global ActionForward "'.$name.'"');
        $this->globalForwards[$name] = $forward;
    }