hook_islandora_derivative defined as
Defines that Object passed can be optional. All implementations in Islandora Core respect that.
Pull 126 in
https://github.com/Islandora/islandora_solution_pack_compound/pull/126#discussion-diff-132515821R292 specifies Abstract Object as required, breaking any implementation, invocation that does not pass an object.
does not make use of an Abstract Object nor requires one in the logic, so can be defaulted to NULL easily or not even needed.