code: private void presistPostInformation(Context appContext, JsonObject postData) {
          preferenceProvider.get(appContext).edit()
                  .putString(String.format(REGISTRAR_PREFERENCE_TEMPLATE, senderId), postData.toString())
                  .commit();
      }
docs: Save the post sent to UPS. This will be used by
  {@link AeroGearUPSMessageService} to refresh the registration
  token if the registration token changes.
  
  @param appContext the application Context