Reference map could not be read

[MightyKnight]

On version 1.20.4, this warning is printed even in the normal game:
Reference map 'de-guntram-mcmod-fabrictools-refmap.json' for mixins.de-guntram-mcmod-fabrictools.json could not be read. If this is a development environment you can ignore this message

I'm pretty sure this is caused by you not having any mixins, but still a mixins json.

It seems you had these mixins in 1.16, maybe you were planning to reimplement them?
But otherwise, unless I misunderstand the usage, you should be able to remove the related files without issues to fix this warning.

Hope this doesn't seem to petty, it's just a small thing I noticed.