[Java] Error using Facebook Android SDK for authentication on Mobile Services .NET Backend

I would like to know if it's possible to use the access token obtained from the Facebook SDK (and/or Google SDK), as authentication for Mobile Services.

My current implementation (shown below), in the callback, continuously returns a 401 error, stating "Error while authenticating user." I tried using the access token string directly but still received the same error.

However, full authentication works if I was to remove the JSON oauth object in the login code.

JsonObject body = new JsonObject();
body.addProperty("access_token", AccessToken.getCurrentAccessToken().getToken());
ListenableFuture<MobileServiceUser> mLogin = mobileServiceClient.login(MobileServiceAuthenticationProvider.Facebook,body);

Thanks,

Eyram