| B | ↘ | C | WC_REST_Coupons_Controller got worse |
| ⇢ | B | WC_REST_Coupons_Controller::update_item() added | |
| ⇢ | B | WC_REST_Coupons_Controller::create_item() added | |
| ⇢ | A | WC_REST_Coupons_Controller::save_coupon() added | |
| B | ↗ | A | WC_REST_Coupons_Controller::add_post_meta_fields() improved |