Caused by java.lang.ClassNotFoundException: Didn't find class "java.util.function.Supplier" on path: DexPathList[[zip file "/data/app/messages.chat.free.text ...

I'm trying to port a Fabric mod that uses LibGui, and I found this. I implemented it and ported everything to NeoForge 1.21.1, but when I try and run it either in the test environment or in an actual ...