Best practice to handle XMS_EXAMPLE_NOTFOUND_ERROR check to support Canonical swagger

We have introduced canonical swagger for [Multi-Versioning in Azure Process (Canonical Version) ](https://microsoft-my.sharepoint.com/:w:/p/jobreen/EdiX_Xv3wzlAoQuJtoQ35m4BwluAe3NuuyFJ40uQBa8AWg?e=K7lV1O). Basically, the canonical swagger file is a union of versioned swaggers.

Here is an example of the canonical swagger in RPSaaSDev branch https://github.com/Azure/azure-rest-api-specs-pr/tree/RPSaaSDev/specification/dinwadevtest/resource-manager/Microsoft.Contoso

When we created a [PR](https://github.com/Azure/azure-rest-api-specs-pr/pull/18958/) for RPSaaSMaster branch, it failed with XMS_EXAMPLE_NOTFOUND_ERROR. We can suppress the error, but want to check what would be the best practice in this case? Can we disable this XMS_EXAMPLE_NOTFOUND_ERROR check when it is for canonical swagger? Thanks.

Start by reviewing the XMS_EXAMPLE_NOTFOUND_ERROR check and the canonical Swagger example described in the issue, then compare the failure reported in PR #18958. Done should be an agreed, documented best practice for handling this check with canonical Swagger, with the expected validation behavior clearly specified.

Written by the indexing model from the issue text.