Proxy configuration

[damonho]

Hi, I have to configure this library to use a proxy that requires authentication.

I see theres a previous issue opened about this #70, however the solution presented there don't quite work with auth.
From square/okhttp#4108, the okhttp library used doesn't respect java.net.Authenticator.setDefault, only java.net.ProxySelector.setDefault.

We have to set the authenticator in the client builder for it to be used.
https://square.github.io/okhttp/3.x/okhttp/okhttp3/OkHttpClient.Builder.html#proxyAuthenticator-okhttp3.Authenticator-

Are we able to add a constructor for the AppStoreServerAPIClient that lets us pass in the OkHttpClient?

[alexanderjordanbaker]

@damonho Would configuring the OKHttpClient client's proxyAuthenticator to be Authenticator.JAVA_NET_AUTHENTICATOR be sufficient for your use case?

[damonho]

@alexanderjordanbaker That sounds like it should work as well for my use case 👍