XEP-0313: Message Archive Management
user send message ‘chat’ or ‘groupchat’
request Message History
Last messages doesn’t resolved in result list.
Monitoring plugin persist messages in every 1 minute. ArchivedMessage are queued to persist.
Service results only persisted message archives in result list. Messages queued to archive aren’t included.
Therefor it is not guaranteed that last messages within 1 minute time space are included in result list.