#fixed code
                                @Override
    public void subscribe(String cluster, Watch.Listener listener) throws Exception {
        listenerMap.putIfAbsent(cluster, new HashSet<>());
        listenerMap.get(cluster).add(listener);
        EtcdWatcher watcher = watcherMap.computeIfAbsent(cluster, w -> new EtcdWatcher(listener));
        executorService.submit(watcher);
    }
#vulnerable code 
                                @Override
    public void subscribe(String cluster, Watch.Listener listener) throws Exception {
        listenerMap.putIfAbsent(cluster, new HashSet<>());
        listenerMap.get(cluster).add(listener);
        EtcdWatcher watcher = watcherMap.computeIfAbsent(cluster, w -> new EtcdWatcher(listener));
        EXECUTOR_SERVICE.submit(watcher);
    } 
                            #location 5 
                            #vulnerability type THREAD_SAFETY_VIOLATION