I'm not a fan of this. My team does this a lot and invariably it leads to having stuff be unfindable because the source you really want is in your build directory and not in code search. Which is annoying but manageable if I build the project, but partners who don't will have an even harder time of things.
More recent efforts have us check in generated code alongside the "config" files, and automated processes ensure you check in the generated code if you touch the config file. It's much better this way.
We generate source code into a "src/main/generated" directory. IntelliJ picks it up like any other source code with proper Gradle configuration and we ignore it with .gitignore.
Only downside we've found is it can be a pain with searching for references in Github and you have to remember to generate the code, but for the most part it is seamless.
I guess how you manage it depends on your IDE, if you can configure it to work nicely, and how much the generated source changes/needs to be read.
More recent efforts have us check in generated code alongside the "config" files, and automated processes ensure you check in the generated code if you touch the config file. It's much better this way.