Consider expected duplicates

[m1kit]

Some templates are similar to each other and may produce duplicated detection.

I found there is a file lists such expected cases.

Hi @goneall, can you tell me about the file?
How is it used and maintained?

[goneall]

@m1kit This file is used by the Github action used to verify changes to the license-list-XML repo. Every PR or merge will run the SPDX Java tools to verify the license XML changes. This includes a check to make sure there isn't already a license definition which matches. The file is provided as an input to the tool.

You should be able to count on this file being maintained and the format being stable if you want to use for yalm-python.

[goneall]

Thinking about this a bit more, perhaps we should replace the "expected-warnings" file with a "known-duplicates.json" file with more precise information. We could store not only the known duplicates, but also the preferred license ID to use when a duplicate is found. Most of the duplicates are due to deprecated license ID's.

This would require a change to the LicenseRdfaGenerator class - but wouldn't be a difficult change to make.