Yet Another CPAN Grep

Dist-Zilla-Plugin-OptionalFeature ( E/ET/ETHER/Dist-Zilla-Plugin-OptionalFeature-0.023.tar.gz, ETHER, 2016; MetaCPAN )

Dist-Zilla-Plugin-OptionalFeature/lib/Dist/Zilla/Plugin/OptionalFeature.pm ( view source; MetaCPAN )

pan-meta/issues/28
    # but this is the current v2.0 spec - regexp lifted from Test::CPAN::Meta::JSON::Version
    $self->log_fatal('invalid syntax for optional feature name \'' .  $self->name . '\''