I was trying to future proof it to some extent - that's why I didn't hard code it to look for the `ServiceActivatorFactoryBean$1` anonymous class (or any class simple name starting with `ServiceActivatorFactoryBean$`).

If someone in future, for some reason, wraps a `MessageHandler` in another `MessageHandler` (regardless of whether it's an `ARPMH` or not) we should not apply metrics to both handlers.