Withers below half health can be hit by shulker bullets

Withers below can be hit by shulker bullets, and will take damage if the projectile has an owner. As wither armor was not detailed in the 12w34b changelog (nor did shulker bullets yet exist), it is unknown whether this is intended, but it seems strange since they are both damaging single-target projectiles like arrows and tridents. (Breezes also have this issue, since MC-266532 was not fully fixed– see the comment on that report.)

To reproduce

1. Launch the game with output enabled

2. /summon wither ~ ~ ~ {Silent:1b,NoAI:1b,Health:10f}

3. /data get entity @s UUID

4. Copy your UUID from the game output

5. Position yourself a couple of blocks west of the wither, and face it

6. /summon minecraft:shulker_bullet ^ ^ ^1 {Motion:[1d,0d,0d],Owner:YOUR_UUID_HERE}
   ❌ The wither is hit by the shulker bullet and flashes red

Expected behavior

The shulker bullet would bounce off like an arrow or trident.