[REQ] Schema preprocessor wanted

Is your feature request related to a problem? Please describe.

My problem is that I am using a schema file (occasionally updated) and there is a double that should be a decimal. I would like to preprocess the schema file to ensure this fix is always present.

Describe the solution you'd like

There are several ways to offer such a preprocessor. One way could be to allow the use of the Overlay Specification, but I don't know if it is finished yet: https://github.com/OAI/Overlay-Specification

I would like for the preprocessor step not create a new file, but make an on-the-fly transformation of the schema file, with optional debug output.

Describe alternatives you've considered

Adding a README file specifying that the schema file must be manually fixed.

Start by reviewing the requested schema-file transformation and the linked Overlay Specification to determine the intended preprocessing model. Compare the proposed on-the-fly transformation and optional debug output with the manual README workaround. Done means an agreed implementation approach that consistently changes the double to a decimal without creating a replacement schema file.