Iron golems can attack villagers.

 If a villager taunts an iron golem with a damage command, the iron golem will attack the villager. This is the cause of MC-195326, but I wrote a separate report.

Steps to Reproduce:

1. Get a villager and iron golem spawn egg
2. Spawn them both next to each other
3. Run to command

   /damage @e[type=minecraft:iron_golem,limit=1,sort=nearest] 0 minecraft:mob_attack by @e[type=minecraft:villager,limit=1,sort=nearest]

Observed Results:
The Iron Golem begins to attack the villagers.

Expected Results:
Just as a Creeper taunts an Iron Golem with a damage command and the Iron Golem doesn't react, the Iron Golem should not attack the villager.