Everything except itemFromName() is not working. Always giving me Steve Heads.

[MarkManFlame55]

Copying the class from here into my project only works if I use Player Names, and adding the repository in pom.xml causes internal Errors (NoClassDefFoundError and ClassNotFoundException). Not sure what is going wrong. I talked with people that use this libraries and show them my code and no one knows what is happening. Any help? Im trying it in 1.20