HttpSender has only private constructors

[robert4os]

Has only private constructors, which are unaccessible outside the library.

[Erni]

I think this is not an issue. Why would you want to construct an HttpSender object? It is meant to be used by the GitkitClient Builder. Not out of here, that's why the constructors are protected.
In any case @liujin-google can give you a better answer in case I am wrong.

[robert4os]

You are right! I have now forked the project and extended GitkitClient to support email verification status. Thank you.