Hi Christian,
I could only have a quick look to your gerrit (even if this is only mainly generated code / icons / tests ;-) ). At the first glance, I say +1 to commit (I will also physically do it on the gerrit).
There are JUnit tests, and I trust you to have them green before posting this message.
I find the solution very elegant. I love for example the databinding for the UMLRTElementProperties in tooling. The documentation that comes around is also very detailed. There may be some impacts, or at least, some places in the code that will benefit from this update, so I would definitely push for it.
The only glitch I could see when browsing the code from a very distant view is the loss of overlays in item providers because the overlayIcon is overriden without call to super(). For example, I don't think that a Capsule will get a submodel decoration, but that would be only a tiny glitch compared to gains.
Finally, thanks for posting this message before pushing to master directly. No worry for getting over gerrit, this tool is supposed to help, not to block ;)
Cheers,
Rémi
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