#vulnerable code 
                                public void start() {
        getNetworkStorage().init();
        List<Node> nodeList = getNetworkStorage().getLocalNodeList(20);
        nodeList.addAll(getSeedNodes());
        for (Node node : nodeList) {
            addNode(node);
        }
        running = true;
        TaskManager.createAndRunThread(NetworkConstant.NETWORK_MODULE_ID, "NetworkNodeManager", this);
        nodeDiscoverHandler.start();
    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                public void start() {
        List<Node> nodeList = getNetworkStorage().getLocalNodeList(20);
        nodeList.addAll(getSeedNodes());
        for (Node node : nodeList) {
            addNode(node);
        }
        running = true;
        TaskManager.createAndRunThread(NetworkConstant.NETWORK_MODULE_ID, "NetworkNodeManager", this);
        nodeDiscoverHandler.start();
    }