[RPaaS LiveValidation] oav doesn't respect x-nullable on parent level

Relevant [Teams thread](https://teams.microsoft.com/l/message/19:b32aaef505e64f9688e09b20f29d5986@thread.skype/1681842153551?tenantId=72f988bf-86f1-41af-91ab-2d7cd011db47&groupId=85d0bde6-230a-4d8d-98f9-43777d9750b2&parentMessageId=1681842153551&teamName=ARM%20Partners&channelName=%5BStackOverflow%5D%20Swagger%20KPIs&createdTime=1681842153551&allowXTenantAccess=false)

[Issue 9629481: Swagger Correctness: MICROSOFT.MEDIA(Media Services)](https://msazure.visualstudio.com/Swagger%20KPIs/_workitems/edit/9629481)

> Renhe Li
>
> I think this is a bug of nullable handling in live validation. primaryVerificationKey is defined as nullable but primaryVerificationKey.@odata.type is required. So in this case, primaryVerificationKey is null, then we should not validate the value of @odata.type again. Ray Chen, did you face similar issue before?

> Ray Chen
>
> Yes, oav doesn't respect x-nullable on parent level. Konrad Jamrozik, can you check with @scbedd who has a task to improve oav for x-nullable validation?

> Sanjid Halim
>
> If it's a false alarm, is there a way to suppress creation of these bugs

@scbedd FYI