* variable lookup.
     *
     * @param props The properties to add the environment variables to, may be {@code null}.
     */
    public static void addEnvVars(Properties props) {
        if (props != null) {
            if (envVars == null) {
                Properties tmp = new Properties();
                boolean caseSensitive = !Os.IS_WINDOWS;

            if (req != null) {
                request.setRemoteRepositories(req.getRemoteRepositories());
            }
        } else {
            Properties props = new Properties();
            EnvironmentUtils.addEnvVars(props);
            props.putAll(System.getProperties());
            request.setSystemProperties(props);
        }

        return request;
    }

    @SuppressWarnings("unchecked")

                && !(e.getCause().getCause() instanceof ArtifactNotFoundException);
    }

    private Properties getSystemProperties() {
        Properties props = new Properties();

        EnvironmentUtils.addEnvVars(props);

        SystemProperties.addSystemProperties(props);

        return props;
    }

    private static final class ProjectRelocation {
        private MavenProject project;