I think this might effect a lot of Facebook/Android developers and yet there does not seem to be that much discussion on the topic...
My question
I don't know Android development, but if you're having issues with that function, maybe there's a similar function of CURL within Android that will allow you to call
https://graph.facebook.com/oauth/access_token?
client_id=APP_ID&
client_secret=APP_SECRET&
grant_type=fb_exchange_token&
fb_exchange_token=EXISTING_ACCESS_TOKEN
(google revealed: http://thesoftwarerogue.blogspot.com/2010/05/porting-of-libcurl-to-android-os-using.html on how to CURL from Android)