SharePoint lifehacks: create SharePoint app registration with client secret which never expires

I bet you know about a page in SharePoint with address AppRegNew.aspx. You use this page to create a new app registration, generate ClientId and ClientSecret. One important thing about ClientSecret generated with AppRegNew.aspx is that that secret has expiration time. By default expiration is 1 year. You can easily replace it afterwards, there is an article out there - Replace an expiring client secret in a SharePoint Add-in. You can even generate a new one with maximum of three years of expiration. Sometimes it’s inconvenient, especially if you have to manage multiple SharePoint apps with different expirations. Do you know, that you can generate a secret, which never expires? Well, technically almost never, but 300 years is pretty good, isn’t it? My ex-college found a way to do that, read further to find out how. More...