+ // We could return null if the delegate is not set yet. In reality though, we do not and should not ever call
+ // this method on DelayedListenerRegistration instances but, since we have to provide an implementation to
+ // satisfy the interface, we throw UnsupportedOperationException to avoid possibly returning null.
+ throw new UnsupportedOperationException(
+ "getInstance should not be called on this instance since it could be null");