TopComponent/setActivatedNodes not workin with a given layer.xml file.

Hi everybody,
I have a NullPointer exception when I use the setActivatedNodes method from a TopComponent. I was able to reproduce the problem in a prototype by adding one of my modules responsible for the platform customization. This module basically contains only a layer.xml file and some  Wstcref and Wsmode files. I cannot figure out what happens with this module that prevents setActivatedNodes to work properly.
Does someone could take a look at this prototype on GitHub? https://github.com/gil-c/DemoPropertiesWindowNotWorking.git. The steps to reproduce the problem are described in the README.md file.
Thanks in advance
Gilles



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