[typespec-azure-core]: function getLroMetadata fails to retrieve finalStateVia in tspfile

[dolauli]

Describe the bug

Below are two cases: one for LRO update and the other for LRO deletion

https://github.com/Azure/azure-rest-api-specs/blob/fa6c6015b1633a701edb629c1a759433aa1fdaf2/specification/scvmm/ScVmm.Management/VmmServer.tsp#L44-L48

https://github.com/Azure/azure-rest-api-specs/blob/fa6c6015b1633a701edb629c1a759433aa1fdaf2/specification/scvmm/ScVmm.Management/VmmServer.tsp#L54-L59

When I attempt to use the following code to retrieve finalStateVia

const lro = getLroMetadata(...);
const finalStateVia = lro.finalStateVia;

Expected value of finalStateVia:

azure-async-operation

Actual value:

location

Reproduction

Added in the description

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For bug in the typespec language or core libraries file it in the TypeSpec repo
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• The provided reproduction is a minimal reproducible example of the bug.

[markcowl]

@dolauli Here is a playground showing how to accomplish this. The idea is that properly-decorated headers need to be specified in the 202 response, and in cases where there are multiple ways to resolve the lro (for example, Azure-AsyncOperation and location header), you can use the @useFinalStateVia decorator to prefer one header over the other in the output.

[dolauli]

Thanks @markcowl for the reply.

The problem I ran into is that there's a bug in the API - getLroMetadata provided in the typespec-azure-core library. Even though azure-async-operation is specified for LRO in the TypeSpec files (as shown in the two examples I provided in the issue description), the API incorrectly returns location for finalStateVia instead of azure-async-operation.

[AllyW]

Things also happened in devcenter

tsp api set pollingLocation on Operation-Location but when we fetch its final-state-via through getLroMetadata(program, op).finalStateVia, we will get original-uri instead. Please have a check about this part.

You can reproduce it by checking this playground and x-ms-long-running-operation-options for @azure-tools/typespec-autorest emitter.