Links to classes moved to `spring-messaging`. Also `MessageHeaders` was inadvertently added back in by the last merge. JIRA: https://jira.springsource.org/browse/INT-3189 __NOTE: Merge to 4.0.0-WIP, not master__
Links to classes moved to `spring-messaging`. Also `MessageHeaders` was inadvertently added back in by the last merge. JIRA: https://jira.springsource.org/browse/INT-3189 __NOTE: Merge to 4.0.0-WIP, not master__