Merge "Throw illegal argument exception when slot index is invalid"

     *

     * @return the lowercase 2 character ISO-3166 country code, or empty string if not available.

     *

     * @throws IllegalArgumentException when the slotIndex is invalid.

     *

     * {@hide}

     */

    @SystemApi

    @RequiresPermission(android.Manifest.permission.READ_PRIVILEGED_PHONE_STATE)

    public String getNetworkCountryIso(int slotIndex) {

        try {

            if (!SubscriptionManager.isValidSlotIndex(slotIndex)) {

                throw new IllegalArgumentException("invalid slot index " + slotIndex);

            }

            ITelephony telephony = getITelephony();

            if (telephony == null) return "";

            return telephony.getNetworkCountryIsoForPhone(slotIndex, getOpPackageName());