@Override
    public Optional<UUID> lookupUniqueId(String username) {
        // get a result from the DB cache
        UUID uniqueId = getStorage().getPlayerUniqueId(username.toLowerCase(Locale.ROOT)).join();

        // fire the event
        uniqueId = getEventDispatcher().dispatchUniqueIdLookup(username, uniqueId);

        // try the servers cache
        if (uniqueId == null && getConfiguration().get(ConfigKeys.USE_SERVER_UUID_CACHE)) {
            uniqueId = getBootstrap().lookupUniqueId(username).orElse(null);
        }

        return Optional.ofNullable(uniqueId);
    }
Performs the initial actions to load the plugin
common/src/main/java/me/lucko/luckperms/common/plugin/AbstractLuckPermsPlugin.java