Remove public "skip path extension" constant

Remove the public constant to make it clearer that skipping path
extensions is really an internal Spring Boot concern.

See gh-8765

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/AbstractEndpointHandlerMapping.java

@@ -29,7 +29,6 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.boot.actuate.endpoint.Endpoint;
-import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration;
 import org.springframework.context.ApplicationContext;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -295,12 +294,13 @@ public abstract class AbstractEndpointHandlerMapping<E extends MvcEndpoint>
 	private static final class SkipPathExtensionContentNegotiation
 			extends HandlerInterceptorAdapter {
 
+		private static final String SKIP_ATTRIBUTE = PathExtensionContentNegotiationStrategy.class
+				.getName() + ".SKIP";
+
 		@Override
 		public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
 				Object handler) throws Exception {
-			request.setAttribute(
-					WebMvcAutoConfiguration.SKIP_PATH_EXTENSION_CONTENT_NEGOTIATION_ATTRIBUTE,
-					Boolean.TRUE);
+			request.setAttribute(SKIP_ATTRIBUTE, Boolean.TRUE);
 			return true;
 		}
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration.java

@@ -153,13 +153,6 @@ public class WebMvcAutoConfiguration {
 
 	public static final String DEFAULT_SUFFIX = "";
 
-	/**
-	 * Attribute that can be added to the web request when the
-	 * {@link PathExtensionContentNegotiationStrategy} should be be skipped.
-	 */
-	public static final String SKIP_PATH_EXTENSION_CONTENT_NEGOTIATION_ATTRIBUTE = PathExtensionContentNegotiationStrategy.class
-			.getName() + ".SKIP";
-
 	@Bean
 	@ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
 	public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
@@ -610,6 +603,9 @@ public class WebMvcAutoConfiguration {
 	static class OptionalPathExtensionContentNegotiationStrategy
 			implements ContentNegotiationStrategy {
 
+		private static final String SKIP_ATTRIBUTE = PathExtensionContentNegotiationStrategy.class
+				.getName() + ".SKIP";
+
 		private final ContentNegotiationStrategy delegate;
 
 		OptionalPathExtensionContentNegotiationStrategy(
@@ -620,8 +616,7 @@ public class WebMvcAutoConfiguration {
 		@Override
 		public List<MediaType> resolveMediaTypes(NativeWebRequest webRequest)
 				throws HttpMediaTypeNotAcceptableException {
-			Object skip = webRequest.getAttribute(
-					SKIP_PATH_EXTENSION_CONTENT_NEGOTIATION_ATTRIBUTE,
+			Object skip = webRequest.getAttribute(SKIP_ATTRIBUTE,
 					RequestAttributes.SCOPE_REQUEST);
 			if (skip != null && Boolean.parseBoolean(skip.toString())) {
 				return Collections.emptyList();