When task and message dispatchers dispatch the events, we trigger somewhat complex sequences of operations that eventually update Pulse tables. Several steps include dependency injection which as of MGNLUI-4180 requires Vaadin UI threadlocal to be set to the correct instance. Unfortunately in the current impl of the dispatchers, we queue the event propagations via VaadinSession#access(..) which doesn't provide the UI instance correctly. Using UI.access(...) in turn provides the UI instance and is a more logically suitable for the task.