Editing an old API revision results in a null pointer exception from the carbon registry Indexing

[Oshanath]

Description

Since APIM does not have any flows that edit past API revisions, this flow has not been tested. But editing past API revision became a requirement with https://github.com/wso2-enterprise/wso2-apim-internal/issues/7431 where we need to decrypt and re-encrypt endpoint secrets stored in past API revisions.

Editing old API revisions result in a Null Pointer Exception due to null being returned from here and that null being accessed here

Steps to Reproduce

1. Log into the publisher portal
2. Deploy the Pizza Shack API
3. Change some configuration and deploy another revision of the API
4. Log into the carbon console and click on browse to browse registry artifacts
5. Expand and click on _system -> governance -> apimgt -> applicationdata -> apis -> [api-uuid] -> [revision] -> api
6. Change something like the port of the endpoint in endpoint configs
7. Click on save API

Version

4.1.0

Environment Details (with versions)

No response