[mtbroker] Trigger.DeliverySpec is ignored

[slinkydeveloper]

Describe the bug
mtbroker trigger does not support delivery spec

Expected behavior
mtbroker trigger should support delivery spec

To Reproduce

1. Create a trigger with a delivery spec, including a dead letter sink
2. Create a sink that always fails
3. Dead letter sink never receives messages

Knative release version
0.24

Additional context
There is no code at all using TriggerSpec.Delivery inside the filter handler

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[lionelvillard]

/remove-lifecycle stale

[lionelvillard]

@pierDipi do you know if this is still the case?

[benmoss]

Using this topology against the latest on the main branch (a6f2a70), it seems to work fine, so I'd say we can close this issue.

[pierDipi]

Yes, I think we can close this, for MTChannelBasedBroker we delegate the retry handling to the underlying Subscription in

eventing/pkg/reconciler/broker/resources/subscription.go

Line 63 in 8274c41

Delivery: delivery,