/usr/share/doc/javacc/examples/Obfuscator/nochangeids is in javacc-doc 5.0-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | // Identifiers that must not be obfuscated.
System
out
println
String
|