How would I move item's persistent data to other item?

So, in a nutshell, I want item to change whenever player joins but save item's persistent data (except display name, lore and similar that accessible not just through getPersistentDataContainer()).
My current code:

Code:

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent event) {
        event.getPlayer().updateInventory();
        event.getPlayer().getInventory().forEach(x -> {
            if (x == null)
                return;

            String id = null;
            try {
                id = x.getItemMeta().getPersistentDataContainer().get(ItemManager.ID_KEY, PersistentDataType.STRING);
            }
            catch (Exception ignored) {
            }
            if (ItemManager.items.containsKey(id)) {
                int count = x.getAmount();
                x = ItemManager.items.get(id).getStack().clone();
                x.setAmount(count);
            }
        });
    }

This code currently saves just item amount, which is nice and all, but I would still like to save item's persistent data (ie custom Enchantments or whatever custom data I'll put on those items)

 

huh? how would i make/add a FileConfiguration thingy and save them there?