public static function appendAddToWishlistFormFields() {
        if (!empty($_REQUEST[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST])) {
            $payload = '';
            if (isset($_GET[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST])) {
                $payload = urlencode($_GET[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST]);
            } else {
                $payload = $_REQUEST[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST];
            }
            ?>
            <input
                type="hidden"
                name="<?php echo Redirect::REDIRECT_KEY_ADD_TO_WISHLIST; ?>"
                value="<?php echo $payload; ?>"
            />
            <?php
            return;
        }

        if (!empty($_REQUEST[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST_BY_SERIAL])) {
            $encodeflag = false;
            if (isset($_GET[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST_BY_SERIAL])) {
                $encodeflag = true;
            }
            foreach ((array)$_REQUEST[Redirect::REDIRECT_KEY_ADD_TO_WISHLIST_BY_SERIAL] as $serial) {
                $payload = $encodeflag === true ? urlencode(wp_unslash($serial)) : wp_unslash($serial);
                ?>
                <input
                    type="hidden"
                    name="<?php echo Redirect::REDIRECT_KEY_ADD_TO_WISHLIST_BY_SERIAL; ?>[]"
                    value="<?php echo $payload ?>"
                />
                <?php
            }
        }
    }