Okay, I've spent a few days getting CardboardSDK-iOS to do what I want (which is like the "Exhibit" demo in Google Cardboard App), and I'm pretty pleased with it. I'm guessing that it's pretty faithfull to the original, but since I'm not familiar with the original, I can't say for sure.
But I can say that it's not just a case of dropping a panoramic data set in. You need to do a bit of work to display the stereo image pair required, in OpenGL, depending on where the viewer has their head pointing. If you understand 3D transforms, how OpenGL works, and you've got your data prepared correctly, it should not be to onerus to get it working.
Of course - this is all done in xcode in ObjectiveC/C++ - and not in Java. And I'm assuming that by "panoramic image" you mean you have a hemispherical stereo data set which should give you something like what you see in Google's Cardboard "Urban Hike" demo.
Hope this helps !