Missing Class in Custom Language Support Tutorial

I am currently using the Custom Language Support Tutorial (1) for my project.

It may be me own fault, but in the third topic a class, named as "SimpleTypes" is referenced. But there is not a single letter about how to create this class and what to put in there.

I hope you are capable of helping me out on this one!

 

Best regards,

Fuchs

 

 

(1): https://www.jetbrains.org/intellij/sdk/docs/tutorials/custom_language_support_tutorial.html