public void damageArmor(EntityLivingBase entity, ItemStack stack,
DamageSource source, int damage, int slot) {
if (!takesDamage(stack, source)) return;
stack.damageItem(damage, entity);
if (stack.stackSize > 0) return;
PropertiesBackpack backpackData = ItemBackpack.getBackpackData(entity);
if (backpackData.contents != null)
for (ItemStack s : backpackData.contents)
WorldUtils.dropStackFromEntity(entity, s, 2.0F);
entity.renderBrokenItemStack(stack);
}