public static synchronized void updateDynmapVersion(String dynmapVersion) {
        if (Main.dynmapVersion != null) {
            if (!Main.dynmapVersion.equals(dynmapVersion)) {
                logger.error("You use different Versions of Dynmaps");
                System.exit(-1);
            }
        } else {
            Main.dynmapVersion = dynmapVersion;
        }
    }