Third party jar to use with qt5 for android

[Kloohtroosht]

Hello

I am trying to load jar library which is described here "AN_233_Java_D2xx_for_Android_API_User_Manual.pdf":http://www.ftdichip.com/Support/Documents/AppNotes/AN_233_Java_D2xx_for_Android_API_User_Manual.pdf

I am using Qt5.1.1

This is sample of code and corresponding debug printout
...
jclass Intent = environment->FindClass("android/content/Intent");
qDebug() << "Intent" << Intent;
jclass Activity = environment->FindClass("android/app/Activity");
qDebug() << "Activity" << Activity;
jclass D2xxManager = environment->FindClass("com/ftdi/j2xx/D2xxManager");
qDebug() << "D2xxManager" << D2xxManager;
jclass FtDeviceInfoListNode = environment->FindClass("com/ftdi/j2xx/D2xxManager$FtDeviceInfoListNode");
qDebug() << "FtDeviceInfoListNode" << FtDeviceInfoListNode;
e = virtualMachine->DetachCurrentThread();
...

D/Qt (17677): ../androjqt/main.cpp:53 (int main(int, char**)): Intent 0x1d200011
D/Qt (17677): ../androjqt/main.cpp:55 (int main(int, char**)): Activity 0x1d200015
D/Qt (17677): ../androjqt/main.cpp:58 (int main(int, char**)): D2xxManager 0x0
D/Qt (17677): ../androjqt/main.cpp:60 (int main(int, char**)): FtDeviceInfoListNode 0x0
E/AndroidRuntime(17677): FATAL EXCEPTION: Thread-398
E/AndroidRuntime(17677): java.lang.NoClassDefFoundError: com/ftdi/j2xx/D2xxManager$FtDeviceInfoListNode
E/AndroidRuntime(17677): at dalvik.system.NativeStart.run(Native Method)
E/AndroidRuntime(17677): Caused by: java.lang.NoClassDefFoundError: com/ftdi/j2xx/D2xxManager
E/AndroidRuntime(17677): ... 1 more
E/AndroidRuntime(17677): Caused by: java.lang.ClassNotFoundException: com.ftdi.j2xx.D2xxManager
E/AndroidRuntime(17677): at dalvik.system.BaseDexClassLoader.findClass(BaseDex ClassLoader.java:61)

Here i see that finding classes in general is working, but my important library can't be found.
I have the two jar files in project/android/libs

I haven't built qt from sources, it is from official binary distribution.

Am i doing something wrong?
Where is some documentation about loading third party jar libraries?

Thank you for any help