#vulnerable code 
                              public static ZkRingGroup create(ZooKeeperPlus zk, String path, ZkDomainGroup domainGroup, Coordinator coordinator) throws KeeperException, InterruptedException, IOException {
    if (domainGroup.getVersions().isEmpty()) {
      throw new IllegalStateException(
          "You cannot create a ring group for a domain group that has no versions!");
    }
    zk.create(path, domainGroup.getName().getBytes());
    zk.create(ZkPath.append(path, CURRENT_VERSION_PATH_SEGMENT), null);
    zk.create(ZkPath.append(path, UPDATING_TO_VERSION_PATH_SEGMENT),
        (Integer.toString(domainGroup.getLatestVersion().getVersionNumber())).getBytes());
    return new ZkRingGroup(zk, path, domainGroup, coordinator);
  } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public static ZkRingGroup create(ZooKeeperPlus zk, String path, ZkDomainGroup domainGroup, Coordinator coordinator) throws KeeperException, InterruptedException, IOException {
    if (domainGroup.getVersions().isEmpty()) {
      throw new IllegalStateException(
          "You cannot create a ring group for a domain group that has no versions!");
    }
    zk.create(path, domainGroup.getName().getBytes());
    zk.create(ZkPath.append(path, CURRENT_VERSION_PATH_SEGMENT), null);
    zk.create(ZkPath.append(path, UPDATING_TO_VERSION_PATH_SEGMENT),
        (Integer.toString(DomainGroupUtils.getLatestVersion(domainGroup).getVersionNumber())).getBytes());
    return new ZkRingGroup(zk, path, domainGroup, coordinator);
  }