Consequently, the community creates (updated) versions. These are unofficial forks where a third-party developer has:
Assuming you have a clean JAR file for version 1206 (or 1213/1165): meteor client 1213 1206 1165 upd
This was an earlier milestone in the legacy branch, likely adding backports of newer GUI features and fixing compatibility issues with the Baritone API (the pathfinding bot integration). Consequently, the community creates (updated) versions