Filter/Predicate validation message are not returned when management.server.port is set for actuator

[abelsromero]

Describe the bug
The feature added in f6bfd6e does not work when user sets a custom management port with management.server.port.

Sample

The test below copied from current test

spring-cloud-gateway/spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/actuate/GatewayControllerEndpointTests.java

Line 182 in 84ddb3e

public void testPostRouteWithNotExistingPredicate() {

when run in SCG repo (main branch) fails with

java.lang.AssertionError: No value at JSON path "$.message"
  ...
Caused by: java.lang.IllegalArgumentException: json can not be null or empty

The only difference with original test is the use of management.server.port=0 to change the port and removal of unnecessary code.

package org.springframework.cloud.gateway.actuate;

import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;

import java.net.URI;
import java.util.Collections;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.actuate.autoconfigure.web.server.LocalManagementPort;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.web.server.LocalServerPort;
import org.springframework.cloud.gateway.handler.predicate.PredicateDefinition;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.test.PermitAllSecurityConfiguration;
import org.springframework.context.annotation.Import;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.reactive.server.WebTestClient;
import org.springframework.web.reactive.function.BodyInserters;

@RunWith(SpringRunner.class)
@SpringBootTest(properties = { "management.endpoints.web.exposure.include=*",
		"spring.cloud.gateway.actuator.verbose.enabled=true",
		"management.server.port=0"
		}, webEnvironment = RANDOM_PORT)
public class GatewayControllerEndpointWithCustomManagementPortTests {

	@Autowired
	WebTestClient testClient;

	@LocalServerPort
	int port;

	@LocalManagementPort
	int managementPort;

	@Test
	public void testPostRouteWithNotExistingPredicate() {

		RouteDefinition testRouteDefinition = new RouteDefinition();
		testRouteDefinition.setUri(URI.create("http://example.org"));

		PredicateDefinition predicateDefinition = new PredicateDefinition("NotExistingPredicate=test-config");
		testRouteDefinition.setPredicates(Collections.singletonList(predicateDefinition));

		testClient.post().uri("http://localhost:" + managementPort + "/actuator/gateway/routes/test-route")
				.accept(MediaType.APPLICATION_JSON).body(BodyInserters.fromValue(testRouteDefinition)).exchange()
				.expectStatus().isBadRequest().expectBody().jsonPath("$.message")
				.isEqualTo("Invalid PredicateDefinition: [NotExistingPredicate]");
	}

	@SpringBootConfiguration
	@EnableAutoConfiguration
	@Import(PermitAllSecurityConfiguration.class)
	static class TestConfig {
	}

}

[abelsromero]

From what we've seen, it seems WebExceptionHandler are loaded in different order running WebFluxResponseStatusExceptionHandler first witch automatically responds.

Without management port

1. ExceptionHandlingWebHander
2. DefaultErrorWebExceptionHandler
3. WebFluxResponseStatusExceptionHandler

With it

1. ExceptionHandlingWebHander
2. WebFluxResponseStatusExceptionHandler
3. DefaultErrorWebExceptionHandler