org.qtproject.qt5.android.bindings.QtActivity -- ClassNotFound exception when built with gradle

[Nelson_Piquet]

I am building my QtApp for android using gradle. The build is successful but when I run my app on device, it gives the following error & crashes

Caused by: java.lang.ClassNotFoundException: Didn't find class "org.qtproject.qt5.android.bindings.QtActivity" on path: DexPathList[[zip file "/data/app/com.mycompany.myapp-1/base.apk"],nativeLibraryDirectories=[/data/app/com.mycompany.myapp-1/lib/arm, /data/app/com.mycompany.myapp-1/base.apk!/lib/armeabi-v7a, /vendor/lib, /system/lib]]

Can someone point why the error is occurring ? Btw, when built with ant, the app builds & runs fine.

My AndroidManifest.xml is exactly like below Qt official example:
http://doc.qt.io/qt-5/qtandroidextras-notification-android-sources-androidmanifest-xml.html

However, I do not have a launcher activity java class. is it absolutely mandatory to have the java class with launcher activity, when building app with gradle & a AndroidManifest file ?

[Nelson_Piquet]

Also, Do I need to set the application name to start the app without crash ?

[Nelson_Piquet]

I have posted the question on stackoverflow with more info. In case you guys have some suggestions, pls reply here as well
http://stackoverflow.com/questions/40084918/building-qtapp-with-gradle-crashes-complaining-unable-to-instantiate-activity