## What
Adding tests to cover `x-expanded-relation` and `x-codegen.queryParams` handling
## Why
The logic that processes these OAS extension can be complex to reason with. Therefore, we should have automated tests to prevent unintentional regression.
## How
* Focus on `getModels` method and its sub-routines.
* Add coverage to getOperation codegen parsing.
* Add coverage to model and operation spec property.
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