INT-3142: A flag to retain default converters when the user has customized messageconverters for HttpRequestHandlingController, HttpInboundGateway
* Introduced a new flag in the base class of HttpRequHttpRequestHandlingController, HttpInboundGateway - registerDefaultConverters
* Introduced a new attribute "register-default-converters" for inbound-channel-adapter and inbound-gateway to indicate if the default HttpMessageConverter's need to be registered
* Http namespace parser related changes to set the new flag
* Added additional tests to test the flag and the namespace parser related changes
Changes per feedback from Artem - additional javadoc comments, cleaned up tests
Updated: Setting the register-default-converters by default to false now, for backward compatibility reasons
Changed adapter name per feedback from Artem
Changed adapter name per feedback from Artem
Changed attribute name from register-default-converters to merge-with-default-converters
INT-3142: Atomic operation for messageConverters
'What's New' polishing
Polishing
Fix a few comments, error messages, docs, whitespace.