*/
private void processGCM(AndroidVariant androidVariant, List<String> registrationIDs, Message gcmMessage, Sender sender) throws IOException {
logger.log(Level.INFO, "Sending payload for [" + registrationIDs.size() + "] devices to GCM");
MulticastResult multicastResult = sender.send(gcmMessage, registrationIDs, 0);
// after sending, let's identify the inactive/invalid registrationIDs and trigger their deletion:
cleanupInvalidRegistrationIDsForVariant(androidVariant.getVariantID(), multicastResult, registrationIDs);
}