[BUG] Missing usage of 'importFileExtension' config in api.mustache for import of common #21540
Description
Bug Report Checklist
- Have you provided a full/minimal spec to reproduce the issue?
- Have you validated the input using an OpenAPI validator?
- Have you tested with the latest master to confirm the issue still exists?
- Have you searched for related issues/PRs?
- What's the actual output vs expected output?
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The original feature pr is #21344 and I forgot to add the config to the api.mustache file.
Attaching a fix for this