NickName doesn't work on PocketMine-MP API 3.0.0-ALPHA5 ?

NickName plugin worked very well but at this time, it has a error...
Here is it:

Code:

ClassNotFoundException: "Class pocketmine\scheduler\CallbackTask not found"
(EXCEPTION) in "/scr/spl/BaseClassLoader" at line 144

(PocketMine-MP phar API 3.0.0-ALPHA5 1.0.7 version)

 

That's normally, CallbackTask no longer exists

 

What should I do?

 

You should stop changing the API definitions in plugins' plugin.yml files without knowing what you're doing.

 

EssentialsPE has a build in nickname system