Wither can break piston extension and end gateway

The bug

The wither boss can break piston extensions and end gateways. For both blocks it displays the missing texture (purple and black) breaking particles.

How to reproduce

1. Summon a wither

   /summon armor_stand ~ ~ ~ {Invulnerable:1b,Passengers:[{id:"wither"}]}

2. Place an affected block in the area in the wither can break

   /execute @e[type=wither,c=1] ~ ~ ~ /setblock ~ ~1 ~ end_gateway

3. Punch the wither to make it break the block

Fix

Add piston_extension and end_gateway to net.minecraft.entity.boss.EntityWither.canDestroyBlock(Block blockIn).