Remove unused field in ResourceHttpRequestHandler

Closes gh-35037

Signed-off-by: 秦利斌 <68638598+Allan-QLB@users.noreply.github.com>

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandler.java

@@ -53,7 +53,6 @@ import org.springframework.util.PathMatcher;
 import org.springframework.util.StringUtils;
 import org.springframework.util.StringValueResolver;
 import org.springframework.web.HttpRequestHandler;
-import org.springframework.web.accept.ContentNegotiationManager;
 import org.springframework.web.context.request.ServletWebRequest;
 import org.springframework.web.context.support.ServletContextResource;
 import org.springframework.web.cors.CorsConfiguration;
@@ -123,8 +122,6 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 
 	private @Nullable ResourceRegionHttpMessageConverter resourceRegionHttpMessageConverter;
 
-	private @Nullable ContentNegotiationManager contentNegotiationManager;
-
 	private final Map<String, MediaType> mediaTypes = new HashMap<>(4);
 
 	private @Nullable CorsConfiguration corsConfiguration;