Searching for a pre-proxy that supports PAC scripts and basic authentication written in JAVA

I'm searching for a proxy server that I can start/stop within Java Code and (in best case) is written in Java. The proxy server must have support for PAC (Proxy-Auto-Config) scripts and should be able to inject username/password to request header for basic authentication. This proxy server should serve as a pre-proxy. Other programs can then use this proxy instead of the PAC script. I found https://github.com/sjitech/proxy-login-automator and it includes PAC support and basic authentication support but it is a node.js script. As a fallback solution I would run the node.js script from Java but a pure Java solution would be preferable to me. Does anyone know another pure Java solution?

Thanks in advance!

There was nothing out there, so I develop my own program. https://github.com/FrankS77/PreProxyFS