What Valgrind is saying is when you exit your application there is still allocated memory in the QMap. Indeed this would be true of any container implementation where you add a bunch of references you never clean-up.
If the object is a long-lived object that lives for the lifetime of the application then it's not really a leak. However if if you ever destroy the object of class KukaDevice you need to ensure you have cleared out the QMap as the stored items will be living in the heap.