How to set proxy using libgit2sharp?

Question

I use libgit2sharp clone and faced "failed to send request: The operation timed out" when I am using corporate networking.

If I use my own 3G networking, it can clone successfully.

But after I use git config in command line and I can clone repository by command line, I still can't clone repository by the code....

could everyone teach me how to set proxy in the code or how to use this lib in proxy environment?

Thanks!