/// <summary>
 /// 获得 MachineGroup 下属于用户并与 Server 端连接的机器状态信息。
 /// </summary>
 /// <param name="client">client实例。</param>
 /// <param name="groupName">用于过滤的机器组名称(支持部分匹配)。</param>
 /// <param name="offset">返回记录的起始位置,默认为 0。</param>
 /// <param name="size">每页返回最大条目,默认 500(最大值)。</param>
 /// <param name="project">项目名,此参数将覆盖 client 中默认设置。</param>
 /// <returns>异步响应结果。</returns>
 /// <seealso cref="ILogServiceClient.ListMachinesAsync"/>
 public static Task <IResponse <ListMachinesResult> > ListMachinesAsync(this ILogServiceClient client,
                                                                        String groupName,
                                                                        Int32 offset = ListMachinesRequest.DefaultOffset, Int32 size = ListMachinesRequest.DefaultSize, String project = null)
 => client.ListMachinesAsync(new ListMachinesRequest(groupName)
 {
     Offset      = offset,
     Size        = size,
     ProjectName = project
 });