JIRA: https://jira.spring.io/browse/INT-3041 Add namespace support to simplify configuration of a `RequestHandlerRetryAdvice. INT-3041 Polishing; PR Comments * Allow a retry-advice element within the request-handler-advice-chain * Clean up schema (should not have allowed `synchronization-factory` on the request-handler-advice-chain. INT-3041 Polishing; PR Comment