WebSphere Portal times out when using Vaadin

Hi guys!
In my proejct I am using Vaadin 6.5.4 (ApplicationPortlet2), the application gets deployed on IBM WebSphere Portal over IBM WebSphere Application Server The issue is that WPS session times out while the user is actively working with a portlet. It seems that WPS doesn’t reckon Vaadin requests as user activity. What is confusing is that WPS session times out at a random moment of time while the is working. So far we haven’t been able to find an exact way to reproduce the issue. I suspect it might have something to do with the issue described in this topic: https://vaadin.com/forum/-/message_boards/view_message/437341. I also suspect that this behaviour started to appear when we migrated from WAS 6 to WAS 7. I’d be thankful for any help!