#vulnerable code 
                                public void shutdown() {
        log.info("ok, shutting down ...");
        synchronized (lock) {
            lock.notify();
        }
    } 
                            #location 2 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                public void shutdown() {
        log.info("ok, shutting down ...");
        if (lock == null) {
            _shutdown();
        }
        else {
            synchronized (lock) {
                lock.notify();
            }
        }
    }