To avoid errors and keep consistency, you should probably have

```
 /**
  * @return Registration
  */
public function setUser(\User_Adapter $user) {}

 /**
  * @return Registration
  */
public function setUsrId($usrId) {}

 /**
  * @return integer
  */
public function getUsrId() {}

 /**
  * @return \User_Adapter
  */
public function getUser(Application $app) {}
```