Thank you for your help. You are most kind, sir :-) I ended up creating a helper AST transform. If you are interested, you can see it here: https://github.com/croz-ltd/klokwrk-project/commit/6f297c96db900d8dabffb45f2a5a38c60e442418
To complete my @Immutable customization story, I also created an AST transform that adds my common post-check in the generated map constructor. You can find it here: https://github.com/croz-ltd/klokwrk-project/commit/724126dac172fecba74a913199ead87223eb4c69 Of course, any comments or suggestions are more than welcome :-) Thank you, Damir
