[Service Bus] Update method under ATOM Management Client

[HarshaNalluru]

Update method allows only a subset of parameters from QueueDescription to be changed, users may get confused by not knowing which ones are updatable.
Should we consider a new options bag for the update method?

https://docs.microsoft.com/en-us/rest/api/servicebus/update-queue

[HarshaNalluru]

Two problems with update requests..

• Default values would override if only a subset of properties of QueueDescription are provided in the request
• The update request with only a subset of attributes from QueueDescription would result in a response that doesn't contain all the attributes from QueueDescription(partial QueueDescription)

Above problems can be avoided by

• Telling users to make a get request before an update request.
  OR
• Doing a get request before update at the SDK level.

[HarshaNalluru]

Final Proposal

• Service returns meaningful error when tried to update something that cannot be updated
• Have user do a GET/CREATE, tweak what needs to be updated, pass it to UPDATE
• Throw error if the input is partial
• Consider adding Etag to the response and pass it to the update request to make sure no other updates have happened in between

[HarshaNalluru]

Questions:

• Update Queue and Update Topic have the docs clearly showing the updatable fields, but not for subscriptions.
  https://docs.microsoft.com/en-us/rest/api/servicebus/update-queue
  https://docs.microsoft.com/en-us/rest/api/servicebus/update-topic
• EnableFilteringMessagesBeforePublishing is not a property on TopicDescription
  Update Topic: https://docs.microsoft.com/en-us/rest/api/servicebus/update-topic
  .NET API View : https://apiview.dev/Assemblies/Review/b5d7e3304000449c859c2016f718db52#Azure.Messaging.ServiceBus.Management.TopicDescription

[ramya-rao-a]

Closing with #9751
Let's log a separate issue for investigating etag use in update operations