How to convert external references to local references

We have dozens APIs that share several common definitions in external files. I am thinking to build a processor to merge all the external references into a final swagger.json and use that to generate models and perform schema validation during runtime. I am just wondering if there is an existing tool that can extract schema from external files and put them into "definitions" section in the final json and update all the external references to local references. Once this is done, there should be a self-contained specification file without any external dependencies. Thanks.

No files, tests, or entry points are named. Start by reviewing the parser's existing handling of external references and determine whether it already supports extracting schemas into a self-contained swagger.json. Done means the external definitions are local and all references no longer require external files.