I need to filter tasks using instance variables. Instead the default behavior of retaining the same user for all tasks in a swimlane, I need to exclude users from performing some tasks in the same swimlane. I could get available tasks for a user and then examine processInstance variables to filter out excluded tasks. But this bleeds workflow into the application. It looks like instance variables are persisted in ways that can't be queried. Is there a way where I could use my defined instance variables as query constraints on queries for tasks?