Wandering llamas ignore attacker(s)

Wandering llamas do not spit at zombies or illagers that attempt to kill their master. 

Steps to Reproduce:
1. Spawn wandering trader, and a zombie/illager
2. Let the mob attack the trader
3. Watch the llamas

Observed Results:
Llamas ignore the attacker(s), allowing their master to be killed.

Expected Results:
Llamas should protect their master by spitting at the attacker(s)