Marking as draft as code is untested

Thank you for your PR. Even though it's a duplicate it's quite interesting to see a different approach. You seem to be missing a way for another plugin to resolve/replace placeholders though? (You don't need to add that if you want to do something else now that you noticed there's a PR for it already. Depends on if @eyvallahabi wants to continue their PR I guess)

But I like the way placeholders can be registered by other plugins in comparison to the other PR, I just feel that it might be more complex than necessary as it basically just mirrors what PAPI does. (I don't really see the usefulness of the author, version and plugin being exposed in the API. Imo. that's an implementation detail of the service provider so a simple Placeholders#registerPlaceholder(Plugin, String id, BiFunction<OfflinePlayer, String, String>) might even be able to handle it with the PAPI extension being constructed inside the provider implementation)

@eyvallahabi maybe you can find a similar but simpler approach for your PR?

Thank you for your PR. Even though it's a duplicate it's quite interesting to see a different approach. You seem to be missing a way for another plugin to resolve/replace placeholders though? (You don't need to add that if you want to do something else now that you noticed there's a PR for it already. Depends on if @eyvallahabi wants to continue their PR I guess)

But I like the way placeholders can be registered by other plugins in comparison to the other PR, I just feel that it might be more complex than necessary as it basically just mirrors what PAPI does. (I don't really see the usefulness of the author, version and plugin being exposed in the API. Imo. that's an implementation detail of the service provider so a simple Placeholders#registerPlaceholder(Plugin, String id, BiFunction<OfflinePlayer, String, String>) might even be able to handle it with the PAPI extension being constructed inside the provider implementation)

@eyvallahabi maybe you can find a similar but simpler approach for your PR?

Thanks for taking the time to reply and look over. You're totally right, I forgot to implement an equivalent of PAPI's setPlaceholders().

My thinking behind copying over the author/version/plugin was that then a server owner or dev or whatever could then trace a placeholder through their provider (PAPI/whomever) to the original, rather than it being traced back to Tresor.
But I do agree it can be removed for the sake of simplifying this PR, and I did feel like I was being too verbose essentially copying over PAPI's interface to this MR :D.

The callback approach you mention probably be the most plugin agnostic approach, would be happy to adopt that too. If the other PR user doesn't come back in the next week or so I'll look at picking this back up, don't want to hijack something they're half-way through.