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

	attach	NIMQChatSystemNotification
	body	NIMQChatSystemNotification
	callbackExt	NIMQChatSystemNotification
	channelId	NIMQChatSystemNotification
	env	NIMQChatSystemNotification
	ext	NIMQChatSystemNotification
	fromAccount	NIMQChatSystemNotification
	fromClientType	NIMQChatSystemNotification
	fromDeviceId	NIMQChatSystemNotification
	fromNick	NIMQChatSystemNotification
	messageClientId	NIMQChatSystemNotification
	messageServerID	NIMQChatSystemNotification
	pushContent	NIMQChatSystemNotification
	pushPayload	NIMQChatSystemNotification
	serverId	NIMQChatSystemNotification
	setting	NIMQChatSystemNotification
	status	NIMQChatSystemNotification
	time	NIMQChatSystemNotification
	toAccids	NIMQChatSystemNotification
	toType	NIMQChatSystemNotification
	type	NIMQChatSystemNotification
	updateTime	NIMQChatSystemNotification