Change Feed Processor: Fixes LeaseLostException on Notifications API for Renewer

[ealsur]

#3401 fixed all the scenarios where the LeaseLostException is generated based on a logical condition (not network request) to contain a CosmosException that is reportable to the Notifications API.

The PartitionSupervisor was modified in that same PR to only report the inner CosmosException to the Notifications API.

However, there was a missing case:

The PartitionController starts a PartitionSupervisor once acquiring a lease, which spans a PartitionProcessor and Renewer.

The Renewer can hit a LeaseLostException if the PartitionProcessor is not processing (idle partition) but being renewed, in that case, the LeaseLostException goes up, stops the PartitionSupervisor as expected, and gets bubbled up to the PartitionController, which releases the lease.

The problem was that the PartitionController calls the Notification APIs to report Errors without identifying that this can only be done for LeaseLostExceptions when they have a linked inner exception (CosmosException). This handling was previously added to other flows (lease acquiring, lease release) but not on the renewal.

Symptoms

This was reported in Azure Functions, where the Functions Extension has a switch statement to log CosmosExceptions:

https://github.com/Azure/azure-webjobs-sdk-extensions/blob/cf0fc8022b230aa1e19325638881a56210474189/src/WebJobs.Extensions.CosmosDB/Trigger/CosmosDBTriggerHealthMonitor.cs#L23-L37

But it is receiving the OuterType as LeaseLostException:

Verification

With this fix, the emitted Notifications/Logs, have the proper Severity Level (Information) and the proper Type (CosmosException):

[FabianMeiswinkel]

LGTM - Thanks