/**
  * @return ServiceProxyFactory
  */
 protected function getServiceProxyFactory($cacheDir = null)
 {
     $serviceProxyFactory = new ServiceProxyFactory();
     $configuration = new Configuration();
     $configuration->setProxiesTargetDir($cacheDir);
     $serviceProxyFactory->setProxyFactory($this->buildProxyFactory($configuration));
     return $serviceProxyFactory;
 }