Hi,
Your developer could simply rename the plugin to authorize2 instead of authorize and it would still work after each update.
If you need to get the current version of the original plugin, download the install package of HikaShop on our website and open it on your computer. There, go in the folder back/extensions/plg_hikashoppayment_authorize/ and you'll find the original files of the plugin.
In fact, you should even still have them in administrator/components/com_hikashop/extensions/plg_hikashoppayment_authorize/ on your website.