Refactor->"Add Definition" not working with empty cpp file

In the "Refactor" context menu entry, "Add Definition in xxx.cpp" does not even show up if the corresponding cpp file has no method definitions at all.

Steps to repeat:
1) Create a new class
2) Add a method declaration in the public section
3) Check the Refactor menu entry --> OK
4) Delete the empty constructor implementation in the cpp file and save
5) Check the Refactor menu entry --> ENTRY MISSING