Method isMergable

src/main/java/com/volmit/adapt/util/Items.java:324–357

Can the item a be stacked onto the item b (following max stack size) @param a the item a @param b the item b @return true if they can be merged

(ItemStack a, ItemStack b)

     * @return true if they can be merged
     */
    @SuppressWarnings("deprecation")
    public static boolean isMergable(ItemStack a, ItemStack b) {
        if (is(a) && is(b)) {
            if (!a.getType().equals(b.getType())) {
                return false;
            }

            if (a.getData().getData() != b.getData().getData()) {
                return false;
            }

            if (a.hasItemMeta() != b.hasItemMeta()) {
                return false;
            }

            if (a.getDurability() != b.getDurability()) {
                return false;
            }

            if (a.hasItemMeta()) {
                if (!a.getItemMeta().getDisplayName().equals(b.getItemMeta().getDisplayName())) {
                    return false;
                }

                if (!new ArrayList<String>(a.getItemMeta().getLore()).equals(new ArrayList<>(b.getItemMeta().getLore()))) {
                    return false;
                }
            }

            return a.getMaxStackSize() >= a.getAmount() + b.getAmount();
        }

        return false;
    }
}