I basically create an empty Java file.
I won't be using the templates because:
Multiple feature files correspond to one Java file
I can't tell if there's no way to reverse the Java code which would be expected if the framework expects one to have a 1 to 1 mapping between DSL file and Java file. Without reversing, I'd delete methods derived from other feature files.
It can be found here: https://eclipse.dev/Xtext/documentation/103_domainmodelnextsteps.html#tutorial-code-generation
I basically create an empty Java file. I won't be using the templates because: