@Nonnull annotation breaks ServletRequestMethodArgumentResolver for Principal

[rcaspar]

If you have something like:

@GetMapping("/foo")
public ResponseEntity<?> method(@Nonnull Principal principal) {
    return ResponseEntity.ok("bar");
}

ServletRequestMethodArgumentResolver will fail to resolve the principal parameter because there's some annotation on it.

I think this is a regression introduced by #19779

[sbrannen]

This is a regression introduced by #25780.

[rstoyanchev]

We might need to fall back on default resolution if a custom resolver didn't resolve it.