code: @Implementation(minSdk = LOLLIPOP_MR1)
    @HiddenApi
    protected int[] getActiveSubscriptionIdList() {
      final List<SubscriptionInfo> infos = getActiveSubscriptionInfoList();
      if (infos == null) {
        return new int[0];
      }
      int[] ids = new int[infos.size()];
      for (int i = 0; i < infos.size(); i++) {
        ids[i] = infos.get(i).getSubscriptionId();
      }
      return ids;
    }
docs: Returns subscription Ids that were set via {@link #setActiveSubscriptionInfoList}.