The new @MVC support classes select a HandlerMethodArgumentResolver
and a HandlerMethodReturnValueHandler statically, i.e. based on
the signature of the method, which means that a controller method
can't declare a more general return type like Object but actually
return a more specific one, e.g. String vs RedirectView, and
expect the right handler to be used.
The fix ensures that a HandlerMethodReturnValueHandler is selected
based on the actual return value type, which is something that was
supported with the old @MVC support classes. One consequence
of the change is the selected HandlerMethodReturnValueHandler can
no longer be cached but that matches the behavior of the old
@MVC support classes.
Issues: SPR-9218
cfe2af7690