What is the Async scope in Mule 4?

The Async scope executes its contained processors asynchronously in a separate thread, while the main flow continues without waiting for the Async scope to complete. Key characteristics:

1. The Async scope receives a copy of the current Mule event at the time it is reached.
2. Changes to payload, variables, or attributes inside the Async scope do not affect the main flow's event.
3. The main flow does not wait — it proceeds immediately after the Async scope starts.
4. Async scopes do not participate in the main flow's transaction — they run in their own context. Use cases: fire-and-forget operations (logging, sending notifications, archiving) where you don't need the result and don't want to delay the main response. Error handling: errors within the Async scope use the default error handler (or a Try scope inside it) — they do not propagate to the calling flow.