#vulnerable code 
                                public static void startNamespaceShardingManagerList(int count) throws Exception {
        assertThat(nestedZkUtils.isStarted());
        for (int i = 0; i < count; i++) {
            shardingRegCenter = new ZookeeperRegistryCenter(new ZookeeperConfiguration(-1, nestedZkUtils.getZkString(), NAMESPACE, 1000, 3000, 3));
            shardingRegCenter.init();
            NamespaceShardingManager namespaceShardingManager = new NamespaceShardingManager((CuratorFramework) shardingRegCenter.getRawClient(),NAMESPACE, "127.0.0.1-" + i);
            namespaceShardingManager.start();
            namespaceShardingManagerList.add(namespaceShardingManager);
        }
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public static void startNamespaceShardingManagerList(int count) throws Exception {
        assertThat(nestedZkUtils.isStarted());
        for (int i = 0; i < count; i++) {
            ZookeeperRegistryCenter shardingRegCenter = new ZookeeperRegistryCenter(new ZookeeperConfiguration(-1, nestedZkUtils.getZkString(), NAMESPACE, 1000, 3000, 3));
            shardingRegCenter.init();
            NamespaceShardingManager namespaceShardingManager = new NamespaceShardingManager((CuratorFramework) shardingRegCenter.getRawClient(),NAMESPACE, "127.0.0.1-" + i);
            namespaceShardingManager.start();
            namespaceShardingManagerList.add(namespaceShardingManager);
        }
    }