[abstract csharp] Ensure enum dataType is not nullable string

[devhl-labs]

This will fix a case where the enum dataType is string? instead of string resulting in code that does not compile. This simply corrects the dataType.

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  ./bin/generate-samples.sh
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@mandrean @frankyjuang @shibayan @Blackclaws @lucamazzanti

[devhl-labs]

circleci failed with 02:53:46.426 [qtp2074407503-16] INFO i.s.sample.resource.PetResource - updatePetWithForm 12830 golang which is not related. AppVeyor failed with Error calling GetPetById: {"code":1,"type":"error","message":"Pet not found"} which I don't see how that can be related.

[wing328]

I saw changes to samples (e.g. scala) not related to this change.

Can you please merge the latest master your branch and update the samples again?

[devhl-labs]

I will do that next week. Im out of town now.

[devhl-labs]

@wing328 Done. Edit-oh i specified csharp when building. Ill do again and build all.

[devhl-labs]

@wing328 Now it's better. Why does did it take 18 commits to change two files 🤣

[wing328]

Gradle, maven plugin test failure already fixed in the master.