JIRA: https://jira.spring.io/browse/INT-3816
Add `cause` `supperclass` mapping ability to the `ErrorMessageExceptionTypeRouter`
Address PR comments:
Introduce `classNameMappings` to store exception classes on the mapping population.
Override all `@ManagedOperation` s to modify `classNameMappings` as well.
Address PR comments:
* Remove redundant local variable
* Fix concurrency access around `channelMapping`
* Add `ClassNotFoundException` test for the `ErrorMessageExceptionTypeRouter`
* Add `What's New` note about the `ClassNotFoundException` during init
Get rid of `synchronized`, use atomic changes
Additional polishing to avoid `ConcurrentModificationException `
Polishing
2d33495437