code: public void setNetworkRoamingStatus(int simSubscriptionId, boolean isNetworkRoaming) {
      if (isNetworkRoaming) {
        roamingSimSubscriptionIds.add(simSubscriptionId);
      } else {
        roamingSimSubscriptionIds.remove(simSubscriptionId);
      }
    }
docs: If isNetworkRoaming is set, it will mark the provided sim subscriptionId as roaming in a local
  cache. If isNetworkRoaming is unset it will remove the subscriptionId from the local cache. The
  local cache is used to provide roaming status returned by {@link #isNetworkRoaming}.