I had the same problem, and annoyingly, I couldn't find anything about this in documentation. You can, however, refer to these two links:
https://developers.facebook.com/docs/android/upgrading-3.x
https://developers.facebook.com/docs/android/upgrading-4x
And induce that your version (3.23.0) is on either Graph API version 2.2 or 2.3 - couldn't quite figure out which one of the two it is. Alternatively it seems that you can call this function from your code:
com.facebook.internal.ServerProtocol.getAPIVersion();
This should return a String of the current Graph API version that you can log. In my case, for SDK version 4.0.1, it was Graph API "v2.3"
Update: It seems that in newer versions of the FB SDK (just tried it in v4.23.0), getApiVersion()
has been changed into getDefaultAPIVersion()
. Seems to do the same thing.