Testing XML files as data sources involves running queries which can take a long time (minutes). I defined my connection URL (in SQuirreL) as jdbc:teiid:VDB@mm://localhost:31000;QueryTimeout=1

The next query I executed processed for over 4 seconds, but there was no evidence of an attempt to cancel the query.

I've got a series of XML files you can use to test this, if you want. They're too big to attach (even when zipped).