Unknown unit type in the-defenders misson (Bug?)

I would like to give some feedback about ...

From: https://py.checkio.org/mission/the-defenders/solve/

HTTP_USER_AGENT:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.67 Safari/537.36

What is a Rookie class? There is no description about it in mission brief.

In my code i have only Warrior, Knight, Defender.