成员的完整列表，这些成员属于 com.netease.nimlib.sdk.msg.SystemMessageService,包括所有继承而来的类成员

clearSystemMessages()	com.netease.nimlib.sdk.msg.SystemMessageService
clearSystemMessagesByType(List< SystemMessageType > types)	com.netease.nimlib.sdk.msg.SystemMessageService
deleteSystemMessage(long messageId)	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessageByType(List< SystemMessageType > types, int offset, int limit)	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessageByTypeBlock(List< SystemMessageType > types, int offset, int limit)	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessages(int offset, int limit)	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessagesBlock(int offset, int limit)	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessageUnread()	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessageUnreadCount()	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessageUnreadCountBlock()	com.netease.nimlib.sdk.msg.SystemMessageService
querySystemMessageUnreadCountByType(List< SystemMessageType > types)	com.netease.nimlib.sdk.msg.SystemMessageService
resetSystemMessageUnreadCount()	com.netease.nimlib.sdk.msg.SystemMessageService
resetSystemMessageUnreadCountByType(List< SystemMessageType > types)	com.netease.nimlib.sdk.msg.SystemMessageService
setSystemMessageRead(long messageId)	com.netease.nimlib.sdk.msg.SystemMessageService
setSystemMessageStatus(long messageId, SystemMessageStatus status)	com.netease.nimlib.sdk.msg.SystemMessageService