Merge pull request #12416 from ahocevar/eventtype-generics

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

src/ol/interaction/Extent.js

@@ -81,6 +81,7 @@ export class ExtentEvent extends Event {
  * This interaction is only supported for mouse devices.
  *
  * @fires ExtentEvent
+ * @extends PointerInteraction<'extentchanged'>
  * @api
  */
 class Extent extends PointerInteraction {