Subject: | please document and test undef_column_value |
Log::Log4perl::Layout::PatternLayout seems to have this config option: https://metacpan.org/source/MSCHILLI/Log-Log4perl-1.46/lib/Log/Log4perl/Layout/PatternLayout.pm#L56
Still I didn't manage to set it using for example "log4perl.appender.SCREEN.layout.undef_column_value": "".
Thanks!