Marcely's Bedwars API Example: ShopGUIBuildEvent

    @EventHandler
    public void test(ShopGUIBuildEvent event){
        if(!(event.getGUI() instanceof GUI))
            return;

        final GUI gui = (GUI) event.getGUI();

        for(int ix=0; ix<9; ix++){
            for(int iy=0; iy<gui.getHeight(); iy++){
                final GUIItem item = gui.getItemAt(ix, iy);

                if(item == null || item.attachment == null || !(item.attachment instanceof ShopItem))
                    continue;

                final ItemStack is = item.getItemStack(); // final itemstack of the shop item
                final ItemMeta im = is.getItemMeta();

                im.setLore(new ArrayList<>()); // example: remove its lore

                is.setItemMeta(im);
            }
        }
    }