Ender Dragons knocks back knockback immune entities

An entity with a knockback resistance of 100% is still affected by the Ender Dragon's knockback.

Command to spawn a knockback resistant villager:

/summon Villager ~ ~ ~ {Age:0,Attributes:[0:{Name:"generic.maxHealth",Base:20.0d},1:{Name:"generic.knockbackResistance",Base:100.0d},2:{Name:"generic.movementSpeed",Base:0.5d},3:{Name:"generic.armor",Base:0.0d},4:{Name:"generic.followRange",Base:16.0d,Modifiers:[0:{Name:"Random spawn bonus",UUIDLeast:-4986886857637389720L,Operation:1,Amount:-0.08103578300212805d,UUIDMost:-9038845231589472274L}]}]}