Man pages matching name lwp::authen::negotiate in section 3pm:

LWP::Authen::Negotiate.3pm.en	debian 10 / liblwp-authen-negotiate-perl
LWP::Authen::Negotiate.3pm.en	debian 11 / liblwp-authen-negotiate-perl
LWP::Authen::Negotiate.3pm.en	debian 12 / liblwp-authen-negotiate-perl