Man pages matching name cpanplus::shell::default::plugins::customsource in section 3pm:

CPANPLUS::Shell::Default::Plugins::CustomSource.3pm.en	debian 10 / libcpanplus-perl
CPANPLUS::Shell::Default::Plugins::CustomSource.3pm.en	debian 11 / libcpanplus-perl
CPANPLUS::Shell::Default::Plugins::CustomSource.3pm.en	debian 12 / libcpanplus-perl