GH-3533: ASB session-id pinning (5.x backport → 5.40.0)

[jeremydmiller]

Backport of #3534 (issue #3533) to the 5.0 maintenance line. Targets the 5.0 branch and bumps the version to 5.40.0 for a NuGet release.

What

Adds an opt-in ServiceBusSessionProcessor-based session listener so competing consumers on one shared Azure Service Bus queue/subscription can each be pinned to their own session id(s). On a shared entity the session id becomes a broker-enforced routing key — a listener pinned to "A" never sees the messages meant for "B".

// Consumer node "A"
opts.ListenToAzureServiceBusQueue("shared-orders")
    .RequireSessionsWithOnlyTheseIdentifiers("A");

// Consumer node "B"
opts.ListenToAzureServiceBusQueue("shared-orders")
    .RequireSessionsWithOnlyTheseIdentifiers("B");

// Producer routes with the session id
await bus.PublishAsync(new OrderPlaced(...), new DeliveryOptions { GroupId = "A" }); // only A receives

Plus the general ConfigureSessionProcessor(Action<ServiceBusSessionProcessorOptions>) hook (multicast) on both queue and subscription listener configs.

Gating / safety

The existing hand-rolled AcceptNextSession loop remains the default; the processor engine only engages when ConfigureSessionProcessor is set (directly or via RequireSessionsWithOnlyTheseIdentifiers). Existing session listeners are untouched. Wolverine reserves ReceiveMode = PeekLock and AutoCompleteMessages = false.

Backport notes

Adapted to the 5.0 code shape, which differs from 6.x:

• 5.0 has no ConfigureProcessor, no IReportConnectionState/AzureServiceBusConnectionStateMapper, and no endpoint PrefetchCount — so the new listener and BuildSessionProcessorOptions are written to the leaner 5.0 shape (session processor options carry no prefetch).
• No conditional compilation needed for net8.0: ServiceBusSessionProcessor, ServiceBusSessionProcessorOptions, CreateSessionProcessor, and ProcessSessionMessageEventArgs are all in Azure.Messaging.ServiceBus regardless of target framework. The project builds clean on net8.0;net9.0;net10.0.

Tests

• Unit coverage for BuildSessionProcessorOptions + both fluent methods.
• An emulator end-to-end test reproducing the issue (listener pinned to "A" receives exactly its messages; a seeded "B" message stays undelivered on the shared queue).

All 8 tests green on net9.0 against the Azure Service Bus emulator; full ASB project builds clean on all three TFMs.

🤖 Generated with Claude Code

https://claude.ai/code/session_01FKAxzuZ36VP6UPcTQf3MUs