[C#] use nullable class in petstore openapi spec

[balassit]

Update petstore spec with more complete testing of nullable properties.

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[balassit]

bug on dictionary type when using nullableReferenceType

[balassit]

nullable reference is not working correctly when enabled on dictionary. From current implementation, it should be treated as Dictionary<string, Object> though subsequently it should be fixed to address as Dictionary<string, Object>?

[balassit]

nullable reference is not working correctly when enabled on dictionary. From current implementation, it should be treated as Dictionary<string, Object?> though subsequently it should be fixed to address as Dictionary<string, Object?>?

[balassit]

nullable reference is not working correctly when enabled on dictionary. From current implementation, it should be treated as Dictionary<string, Object> though subsequently it should be fixed to address as Dictionary<string, Object>?

[balassit]

nullable reference is not working correctly when enabled on dictionary. From current implementation, it should be treated as Dictionary<string, Object?> though subsequently it should be fixed to address as Dictionary<string, Object?>?