The last update changed the entire project to be compiled with Java 16. However, this breaks the plugin whenever you use an earlier Java version with an earlier version of Spigot (e.g. Spigot 1.16.5 on Java 8).

This fixes this issue by compiling only the 1.17 part of the plugin with Java 16 and the rest of the code is still compiled with Java 8 as it has been in the past.

Note that if you are already running the last update posted on Java 16 and Spigot 1.17, there is no need to update to this build.