Fix RequestMapping logic according latest Spring MVC changes [INT-3713]

[spring-operator]

Artem Bilan opened INT-3713 and commented

The latest MVC changes has this new condition:

MappingDefinition<T> definition = this.methodLookup.get(newHandlerMethod.getMethod());
if (definition != null) {
	throw new IllegalStateException("Cannot map " + newHandlerMethod.getMethod() +
	"\nto " + mapping + ".\n It is already mapped to " + definition.getMapping());
}

See linked Spring Framework issue.

The usage common private static final Method HANDLE_REQUEST_METHOD for all Integration handleRequest isn't valid any more.

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Reference URL: https://build.spring.io/browse/INT-MEIGHT-226

Issue Links:

• SPR-11541 Provide public methods to register and un-register handler method mappings
  ("depends on")

Referenced from: pull request #1434