This commit updates the RequestMappingHandlerMapping implementations in
Spring MVC and Spring WebFlux so that mixed @RequestMapping and
@HttpExchange declarations on the same element are rejected.
Note, however, that a @Controller class which implements an interface
annotated with @HttpExchange annotations can still inherit the
@HttpExchange declarations from the interface or optionally override
them locally with @HttpExchange or @RequestMapping annotations.
See gh-31962
See gh-32049
Closes gh-32065