static String addQueryParams(String path, @Nullable QueryParams params) {
        requireNonNull(path, "path");
        if (params == null || params.isEmpty()) {
            return path;
        }

        final StringBuilder appendedPath = new StringBuilder(path);
        if (path.indexOf('?') == -1) {
            appendedPath.append('?');
        } else {
            appendedPath.append('&');
        }
        return params.appendQueryString(appendedPath).toString();
    }
Appends query params to the current path and returns the modified path.
core/src/main/java/com/linecorp/armeria/client/WebClientUtil.java