ThreadLocal error on server shutdown

I get the below entry twice in my server.log when I shutdown my Glassfish 4.1 server.
Any one got any ideas of why or where to look?

[glassfish 4.1]
[tid: _ThreadID=218 _ThreadName=RunLevelControllerThread-1499973694504]
[timeMillis: 1499973694582]
[levelValue: 1000]

The web application
[/MyAppUi] created a ThreadLocal with key of type [com.vaadin.util.CurrentInstance$1]
(value [com.vaadin.util.CurrentInstance$1@4074a671]
) and a value of type [java.util.HashMap]
(value [{class com.vaadin.server.VaadinService=com.vaadin.util.CurrentInstance@2a4a81bc, class com.vaadin.ui.UI=com.vaadin.util.CurrentInstance@43d0111e, class com.vaadin.server.VaadinSession=com.vaadin.util.CurrentInstance@459dc001}]
) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.]]

Best I can say without any more details is that you could try to run something like
to see what’s the cause of the issue.

Thanks I’ll give it a try.