Fix race condition in GatewayInterfaceTests

Author: artembilan

spring-integration-core/src/test/java/org/springframework/integration/gateway/GatewayInterfaceTests.java

@@ -678,7 +678,7 @@ public MessageChannel gatewayChannel() {
 		}
 
 		@Bean
-		@BridgeTo(poller = @Poller(fixedDelay = "1000"))
+		@BridgeTo(value = "nullChannel", poller = @Poller(fixedDelay = "1000"))
 		public MessageChannel gatewayQueueChannel() {
 			return new QueueChannel();
 		}