Hi there,
I was testing out Vaadin 7.2.0.beta1 with the hopes of being able to take advantage of some of the performance improvements made in this version. I specifically set my transport mode to HTTP streaming because I am not able to use the websockets transport mode because of a known issue with websockets and CDI (http://dev.vaadin.com/ticket/12464), however once I did that I noticed that a Nullpointer Exception is occuring shortly after starting the application with changes being automtically pushed to the UI. This issue is easily reproducible, but I have attached a sample project which you can run to reproduce the issue on your end, as well as a file containing the stack trace of the nullpointer exception being thrown from the vaadin-server jar. The sample project was created using eclipse, so you will need to import it using eclipse.
Using: Eclipse, JDK 1.7.0_51, Wildfly 8, and Firefox browser for testing.
After running the sample application for less than 5 minutes the nullpointer exception will occur.