JIRA: https://jira.spring.io/browse/INT-4203
Add channel names for easier use in DSL.
Add documentation (boot) example.
Normalize Expression Setters; add Javadocs
Polishing - SPR-15091
Tiny code style polishing
Conflicts:
spring-integration-core/src/test/java/org/springframework/integration/dsl/flows/IntegrationFlowTests.java
src/reference/asciidoc/handler-advice.adoc
spring-integration-core/src/test/java/org/springframework/integration/handler/advice/ExpressionEvaluatingRequestHandlerAdviceTests.java
* Restore removed methods in the `ExpressionEvaluatingRequestHandlerAdvice` and deprecate them
* Remove methods in the `ExpressionEvaluatingRequestHandlerAdvice` introduced since `5.0`
3301da4157