Why can I get an Google Health AuthSub Token using https://www.google.com/accounts/AuthSubRequest?
Google Health uses its own AuthSub service at https://www.google.com/health/authsub. The Google Data client library does not create the correct URL for Google Health’s AuthSub service. You should either edit the Google Data client library source code or replace the AuthSub part of the generated URL (“/accounts/AuthSubRequest”) with the correct Google Health AuthSub service (“/health/authsub”).