Prior to this commit, the resolveBean() method in ControllerAdviceBean
looked up the @ControllerAdvice bean instance in the ApplicationContext
by name for every web request that involved lookups for global methods
annotated with @ExceptionHandler, @InitBinder, and @ModelAttribute.
This commit avoids the need for such repeated lookups in the
ApplicationContext by caching the resolved @ControllerAdvice bean
instance within ControllerAdviceBean once it has been resolved.
21267e56b7