When querying MAM archive of a MUC room and when there aren't any items left and <fin/> is return it lacks `complete` attribute:

https://xmpp.org/extensions/xep-0313.html#query-paging-request
> When the results returned by the server are complete (that is: when they have not been limited by the maximum size of the result page (either as specified or enforced by the server)), the server MUST include a 'complete' attribute on the <fin> element, with a value of 'true'; this informs the client that it doesn't need to perform further paging to retreive the requested data. If it is not the last page of the result set, the server MUST either omit the 'complete' attribute, or give it a value of 'false'.

 
Example:

Request
```xml

<iq type='set' to='smack@conference.igniterealtime.org' id='AC4C54D1-261C-40E6-BC82-5F2C6DD64B3E'>
<query xmlns='urn:xmpp:mam:2' queryid='A747F17C-B623-493E-B93B-E0C60CC822A2'>
<x type='submit' xmlns='jabber:x:data'>
<field type='hidden' var='FORM_TYPE'>
<value>urn:xmpp:mam:2</value>
</field>
<field type='text-single' var='start'>
<value>2020-07-30T20:54:48Z</value>
</field>
<field type='text-single' var='end'>
<value>2020-08-03T16:02:16Z</value>
</field>
</x>
<set xmlns='http://jabber.org/protocol/rsm'>
<max>150</max>
</set>
</query>
</iq>
```

Response (lacking `complete` attribute):
```xml
<iq to='wojtek@tigase.org/1505915227-tigase-19' from='openfire@conference.igniterealtime.org' id='1B867B69-40BE-4EDA-A68A-D6CFA7E0F99E' type='result' xmlns='jabber:client'>
<fin queryid='B60B9A76-9E13-4C43-8D0D-B30E15C807E3' xmlns='urn:xmpp:mam:2'>
<set xmlns='http://jabber.org/protocol/rsm'>
<count>0</count>
</set>
</fin>
</iq>

```