Activate Annotation of synthetic members in Xtext's Oomph setup

[HannesWell]

Explicitly activate the Xtend compiler preference Annotate synthetic members with @XbaseGenerated.
The generated code committed to the repository uses that and if one has disabled once it will generate diffs in the Git worktree.
So the Oomph setup should explicitly activate that Option.

[github-actions]

Test Results

  6 461 files  + 1 609    6 461 suites  +1 609   3h 12m 29s ⏱️ + 56m 3s
 43 236 tests ±     0   42 652 ✅ ±     0    584 💤 ±  0  0 ❌ ±0 
170 059 runs  +42 540  167 722 ✅ +41 956  2 337 💤 +584  0 ❌ ±0 

Results for commit 6893930. ± Comparison against base commit 99a5c22.

[HannesWell]

@cdietrich, @LorenzoBettini is this good to go?

[LorenzoBettini]

I'm fine with that, though I haven't manually tested, it's good to ensure it's set. If @cdietrich is ok, I'd merge.

[cdietrich]

i cant judge sry. no mental capaity

[szarnekow]

Hmm curious. I expected all projects to have project specific settings.

[LorenzoBettini]

Hmm curious. I expected all projects to have project specific settings.

I think so, but I added that option recently and I guess project settings haven't been updated. By default that setting is on.

Maybe we should update all settings accordingly.

[HannesWell]

By default that setting is on.

It is one by default but disabled it in the workspace because when introduced initially I had problems with it for a short time:

• Xtend generates invalid code for extending dispatch method #3182 (comment)

Then I forgot about it and later had differing code. Therefore I thought that nowadays it would be good to ensure its always active.

Maybe we should update all settings accordingly.

When that is done, this could be reverted, yes.