Fix DMLC Unknown Host Test

Use a custom address resolver instead of using DNS.

Author: garyrussell

spring-rabbit/src/test/java/org/springframework/amqp/rabbit/listener/DirectMessageListenerContainerIntegrationTests.java

@@ -28,6 +28,7 @@
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
+import java.net.UnknownHostException;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
@@ -184,6 +185,9 @@ public void testSimple() throws Exception {
 	@Test
 	public void testBadHost() throws InterruptedException {
 		CachingConnectionFactory cf = new CachingConnectionFactory("this.host.does.not.exist");
+		cf.setAddressResolver(() -> {
+			throw new UnknownHostException("Test Unknown Host");
+		});
 		ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
 		executor.setThreadNamePrefix("client-");
 		executor.afterPropertiesSet();