code: @Implementation(minSdk = LOLLIPOP_MR1, maxSdk = P)
    @HiddenApi
    protected static int getPhoneId(int subId) {
      if (phoneIds.containsKey(subId)) {
        return phoneIds.get(subId);
      }
      return INVALID_PHONE_INDEX;
    }
docs: Uses the map of subscription IDs to phone IDs managed by {@link putPhoneId} and {@link
  removePhoneId} to return the phone ID for a given subscription ID.