Upgrade jflex.
Change doesn't alter the behavior of any of the analyzers (unicode
version or grammar refactorings), just the minimal to get new tooling
working.
This has the same logic as the previous python, but no longer relies
upon parsing HTML output, instead using java's doclet processor.
The errors are reported like "normal" javadoc errors with source file
name and line number and happen when running "gradlew javadoc"
Although the "rules" are the same as the previous python, the python had
some bugs where the checker didn't quite do exactly what we wanted, so
some fixes were applied throughout.
Co-authored-by: Dawid Weiss <dawid.weiss@carrotsearch.com>
Co-authored-by: Uwe Schindler <uschindler@apache.org>