Symfony-MemcachedAdapter::\u construct()必须是Memcached的实例,给定字符串

框架.yaml

framework:
    cache:
        app: app.memcached_adapter

服务.yaml

app.memcached_client:
    class: Memcached
    factory: 'Symfony\Component\Cache\Adapter\MemcachedAdapter::createConnection'
    arguments: [['%app.memcached.dsn.1%', '%app.memcached.dsn.2%']]
    public: true

app.memcached_adapter:
    class: Symfony\Component\Cache\Adapter\MemcachedAdapter
    arguments:
        - '@app.memcached_client'
    public: true

Type error: Argument 1 passed to Symfony\Component\Cache\Adapter\MemcachedAdapter::__construct() 
must be an instance of Memcached, string given, called in 
/users/me/project/please-dont-mention-the-company/sports/var/cache/lcl/ContainerXqbuh45/srcLclDebugProjectContainer.php 
on line 1029

在查看上述生成的容器类时,我发现:

/**
 * Gets the public 'cache.app' shared service.
 *
 * @return \Symfony\Component\Cache\Adapter\TraceableAdapter
 */
protected function getCache_AppService()
{
    return $this->services['cache.app'] = new \Symfony\Component\Cache\Adapter\TraceableAdapter(new \Symfony\Component\Cache\Adapter\MemcachedAdapter('kRTmoLLARw'));
}

我不知道它是如何用那个字符串作为参数生成的,它应该是memcached客户端!

有什么想法吗?我可以在不调试容器类生成的情况下检查任何内容?