justauth/JustAuth ? reverse-engineered prompt

Build me a simple Java library for third party login that makes social sign in really easy for other projects to use.

I want it to support a bunch of popular providers like GitHub, Gitee, WeChat, QQ, Google, Facebook, Twitter, Slack, and similar services, with one clean way to get the login link and handle the callback after the user approves access. Please make it easy to set client id, client secret, redirect url, and state, and let me plug in my own cache, my own HTTP client, and even add a custom provider if I need one.

It should feel lightweight, work on JDK 8 or newer, include clear examples and docs, and be easy to copy into a Spring or plain Java project. If there are any current best practices or provider details I should follow, look them up online and use the latest info.