@EventHandler
public void onHitPlayer(EntityDamageByEntityEvent event){
	player.setVelocity(new Vector(0, 2, 0)); //This one doesn't work
	player.setVelocity(new Vector(2, 0, 2)); //This one works
}

After listening for an EntityDamageByEntityEvent and attempting to change the player's velocity, it will work on the x and z axis, however does not work on the y axis. It seems as though the damage vector is overriding the y axis of the new vector, but not the x and z