Fixes spring-cloudgh-2933 GatewayFilter support @order annotation

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/handler/FilteringWebHandler.java

@@ -30,6 +30,7 @@
 import org.springframework.cloud.gateway.filter.OrderedGatewayFilter;
 import org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory;
 import org.springframework.cloud.gateway.route.Route;
+import org.springframework.core.DecoratingProxy;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.web.server.ServerWebExchange;
@@ -43,6 +44,7 @@
  *
  * @author Rossen Stoyanchev
  * @author Spencer Gibb
+ * @author Yuxin Wang
  * @since 0.1
  */
 public class FilteringWebHandler implements WebHandler {
@@ -124,7 +126,7 @@ public Mono<Void> filter(ServerWebExchange exchange) {
 
 	}
 
-	private static class GatewayFilterAdapter implements GatewayFilter {
+	private static class GatewayFilterAdapter implements GatewayFilter, DecoratingProxy {
 
 		private final GlobalFilter delegate;
 
@@ -145,6 +147,11 @@ public String toString() {
 			return sb.toString();
 		}
 
+		@Override
+		public Class<?> getDecoratedClass() {
+			return delegate.getClass();
+		}
+
 	}
 
 }