Make it possible to place models in a different package to prevent circular package references for go-server (!11623) · Merge requests · OpenAPI Tools / openapi-generator

Created by: Kraust

Continuing the work started in https://github.com/OpenAPITools/openapi-generator/pull/9089. After merging master into the original branch I discovered several other pieces that needed updating that lead me to create https://github.com/OpenAPITools/openapi-generator/issues/11622 and refactor a bit of the code (the supporting files are now in their own directory as they're shared by both the APIs and Models).

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```
./mvnw clean package 
./bin/generate-samples.sh
./bin/utils/export_docs_generators.sh
```
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