How to build app compliant with Google Play 64-bit requirement?

Question

After I upload the APK to play store I got the following warning. What changes should I make to release an APK build with flutter SDK to meet the 64-bit requirement?

Answer 1

Now there is a new better solution provided by the futter team.
You need to use the new flutter version 1.7.12. (my setup)

Flutter 1.7.12-pre.40 • channel master • https://github.com/flutter/flutter.git
Framework • revision 3badcf51a4 (13 hours ago) • 2019-06-28 15:14:03 -0700
Engine • revision e96900df2f
Tools • Dart 2.4.0

Then you can build your (single) app bundle for x86 and x64 with this command.
flutter build appbundle

Additional you can add --release --target-platform android-arm,android-arm64. But this might cause a broken app...