Use generics to limit event types in on(), once() and un()

src/ol/interaction/Modify.js

@@ -183,6 +183,7 @@ export class ModifyEvent extends Event {
  * key is pressed.  To configure the interaction with a different condition
  * for deletion, use the `deleteCondition` option.
  * @fires ModifyEvent
+ * @extends PointerInteraction<'modifyend'|'modifystart'>
  * @api
  */
 class Modify extends PointerInteraction {