CrossRegionHedging: Fixes NullReference Exception Bug

[dibahlfi]

Pull Request Template

Description

This change is to fix CosmosNullReferenceException that happens when a client passes a CancellationToken along with the request. Please see(#4737) for more information.

Type of change

Please delete options that are not relevant.

• [] Bug fix (non-breaking change which fixes an issue)

Closing issues

To automatically close an issue: closes #4737

[kundadebdatta]

One minor comment. Otherwise, LGTM.

[NaluTripician]

A few nits other than that LGTM. Good work, thanks!

[kirankumarkolli]

@NaluTripician curious who is the consumer for below snipper (its unrelated to this PR)

                                if (completedTask.IsFaulted)
                                {
                                    AggregateException innerExceptions = completedTask.Exception.Flatten();
                                }

[NaluTripician]

If I recall correctly from when we added this, it is needed for if there is an exception that needs to be thrown to the customer

[kirankumarkolli]

Its only getting the exception and not using it.
Below await does throw in-case of exceptions?

[kirankumarkolli]

@NaluTripician can you please follow-up on this?
And resolve this comment.

[NaluTripician]

Yes, we throw if there was an exception and there are no more regions to hedge to

[sourabh1007]

We are changing the behavior here, previously if operation was cancelled due to cancellation token, it used to return a valid HedgingResponse, now we are returning exception. Is this expected?

[NaluTripician]

LGTM - thanks!

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