The Shake effect done to a zombie villager shakes their body, but not their head

The Shake effect done to a zombie villager while converting to a villager shakes their body, but not their head.

Steps to Reproduce:

1. Spawn a zombie villager in a shaded area
2. Throw a splash potion of weakness at it
3. Feed it a golden apple

Observed Results:
The zombie villager's body shakes, but the head does not.

Expected Results:
The head should also shake.