The bytecode format is well-documented. If Lombok would just augment these, then there would be no major problem with it. But it actually does something worse:

The bytecode format is well-documented. If Lombok would just augment these, then there would be no major problem with it. But it actually does something worse: it uses reflection and other tricks to extend the Abstract Syntax Tree, which is purely an implementation detail of the Java compiler. And it must do the same with every tool that touches Java Sources.