RT::Extension::MandatoryOnTransition

This RT extension enforces that certain fields have values before
tickets are explicitly moved to or from specified statuses. If you list
custom fields which must have a value before a ticket is resolved, those
custom fields will automatically show up on the "Resolve" page. The
reply/comment won't be allowed until a value is provided.

WWW: https://metacpan.org/release/RT-Extension-MandatoryOnTransition