I am also an Android developer. I tried with Android SDK. If you use the code from master branch, it could not work with DF2.0 or DF 1.9x. "No value for session_token" is because the format of response is not same as the code expected. I am very disappointed with that SDK, it wasted me a lot of time checking the differences and filling the gap. Now, I am writing Android SDK by myself, it is quite easy than using the public one.