Man pages matching name html::widget::filter::whitespace in section 3pm:

HTML::Widget::Filter::Whitespace.3pm.en	debian 10 / libhtml-widget-perl
HTML::Widget::Filter::Whitespace.3pm.en	debian 11 / libhtml-widget-perl
HTML::Widget::Filter::Whitespace.3pm.en	debian 12 / libhtml-widget-perl