使用fluent-logger-java将日志推到fluentd中FluentLogger空指针异常？

Question

 private static FluentLogger LOG = FluentLogger.getLogger("fluentd.test");

    public void doApplicationLogic() {
        // ...
        Map<String, Object> data = new HashMap<String, Object>();
        data.put("from", "userA");
        data.put("to", "userB");
        LOG.log("follow", data);
        // ...
    }

程序第一次运行时正常，第二次运行就报空指针异常