How to get the "user_id" trace

[AdrianSanchezLopez]

Hi everyone, not sure if this is the right place to ask this question so apologize for it beforehand.
Is there a way of tracing back the "user_id" this plugin sends?

I can see in code the "user_id" field, but how could I get the original moodle User ID (on the moodle database) from it? I do have the Consumer key, Shared Key, moodle DB access, etc .. but I'm not too familiar of how to "reverse" it from there.

This issue is very important for us at the moment, because of some legal requirements regarding the users identification in out moodle.
Thank you very much!