Llama's unaffected by Thorns

While wearing armor with the thorns enchantment, I was messing with a Trader Llama that was attacking me, and I noticed that it didn't take damage from the thorns. I tested with regular Llama's in a creative world, and they didn't take any damage either. When a Ghast shoots a fireball at you, it takes damage from it, so why don't Llama's and Trader Llama's?

Expected Result

Llamas would take damage from thorns when spitting at you with thorns