I got confirmation from another user in the google-api-java-client group. The workaround is to drop UrlFetchTransport and use NetHttpTransport which seems to be supported nowadays on AppEngine.
see here : https://groups.google.com/forum/?fromgroups#!topic/google-api-java-client/FJSsz5qo7pg My app is working in production now. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/4iU7f_3ZXaAJ. To post to this group, send email to google-appengine@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
