I am having a weird behaviour where I am correctly stepping into my portlet code writing html fragment. The point is the resulting page is empty (view source page is empty).
The fact is that I have changed the organisation of pages and windows and this weird behavior is probably a mistake I made.
I tried to follow the code but this interceptor thing is hard to follow, which class should I trace to get a chance to understand what is going on?
I started with 2.6.2 bundled and a fresh database.
Found and fixed.: The URI in my layouts.xml file were wrong.