Thanks a lot for the feedback and the invaluable reproducer!
I reproduced the issue on my side and created the following ticket on our Java Analyzer to try to fix it: SONARJAVA-3607.
This is definitely a bug, which will probably be quite tricky to fix. Lombok is tricking the ECJ parser here, apparently because the static constructorsof(), generated in bytecode thanks to the Lombok annotation, are not visible from within the class declaration itself, although being in the same compilation unit as the rest of the code.
We will see what we can do! In the meantime, only the file causing this parse error will be skipped during your analysis.