成员的完整列表，这些成员属于 NIMQChatMarkSystemNotificationsReadParam,包括所有继承而来的类成员

cb	NIMQChatMarkSystemNotificationsReadParam
mark_read_infos	NIMQChatMarkSystemNotificationsReadParam
mark_read_infos_count	NIMQChatMarkSystemNotificationsReadParam
user_data	NIMQChatMarkSystemNotificationsReadParam