Fix issue in ContentNeogitatingViewResolver

The following commit in 3.2.3 had a side effect on CNVR:
aaded7e30b

It appears that CNVR doesn't treat a request for "*/*" differently
from a request that does not request content types. Both should be
interpreted as "any content type is acceptable". This fix ensures
that CNVR treats these two cases the same way.

Issue: SPR-10683

spring-webmvc/src/test/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolverTests.java

@@ -46,6 +46,7 @@ import org.springframework.web.servlet.ViewResolver;
 
 import static org.junit.Assert.*;
 import static org.mockito.BDDMockito.*;
+import static org.mockito.Mockito.*;
 
 /**
  * @author Arjen Poutsma