+ # return [], [] if $self->items_checksum eq $comparison_part->items_checksum;
+ my @self_part_ids = map { $_->parts_id } $self->items;
+ my @comparison_part_ids = map { $_->parts_id } $comparison_part->items;
+
+ my %orig = map{ $_ => 1 } @self_part_ids;
+ my %comparison = map{ $_ => 1 } @comparison_part_ids;
+ my (@additions, @removals);
+ @additions = grep { !exists( $orig{$_} ) } @comparison_part_ids if @comparison_part_ids;
+ @removals = grep { !exists( $comparison{$_} ) } @self_part_ids if @self_part_ids;