Withers and wither skeletons will be killed by the wither damage of the /damage command, even if they are immune to wither damage

The bug

Withers and wither skeletons will be killed by the wither damage of the /damage command, even if they are immune to wither damage.

Reproduce steps

1. Summon a wither or wither skeleton.
2. Use the /damage command:
   Wither

   /damage @e[type=wither,limit=1] 500 minecraft:wither at 88 65 1

   Wither skeleton

   /damage @e[type=wither_skeleton,limit=1] 500 minecraft:wither at 88 65 1

3. Found them all withered away.

Expected to happen...

• Using the /damage with wither type should not damage withering-immune mobs.