JIRA: https://jira.spring.io/browse/INT-3500
* add 'error-channel' to the <enricher> component
* delegate errorChannel to the internal gateway in ContentEnricher
* added tests for xml based and java based enrichers with error channels
INT-3500: Consider to add "error-channel" to the <enricher>
* Fixed typos and comments
* Reworked xml integration test to use the outputChannel and increased timeout
* Added overview in whats-new doc
INT-3500: Consider to add "error-channel" to the <enricher>
* Ensure requestChannel is set if an errorChannel is set
* Increased timeout to fix unit test
* Added details to content-enricher ref doc
Polishing
30b58836e5