For an unknown reason, when I tried to build my Google App Engine endpoints, I get these errors in all of the API java files generated by Android Studio:
Err
Faced the same problem. I upgraded google client libs to 1.23.0 and it worked (earlier was 1.22.0)
compile 'com.google.api-client:google-api-client:1.23.0' compile 'com.google.http-client:google-http-client-android:1.23.0'