Fix STOMP broker relay int test issue

Avoid dependency on order in which expected messages are received.

spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerIntegrationTests.java

@@ -282,11 +282,28 @@ public class StompBrokerRelayMessageHandlerIntegrationTests {
 		}
 
 		public void expectMessages(MessageExchange... messageExchanges) throws InterruptedException {
-			for (MessageExchange exchange : messageExchanges) {
+
+			List<MessageExchange> expectedMessages =
+					new ArrayList<MessageExchange>(Arrays.<MessageExchange>asList(messageExchanges));
+
+			while (expectedMessages.size() > 0) {
 				Message<?> message = this.queue.poll(10000, TimeUnit.MILLISECONDS);
-				assertNotNull("Timed out waiting for: " + exchange, message);
-				assertTrue("Expected: " + exchange + " but got: " + message, exchange.matchMessage(message));
+				assertNotNull("Timed out waiting for messages, expected [" + expectedMessages + "]", message);
+
+				MessageExchange match = findMatch(expectedMessages, message);
+				assertNotNull("Unexpected message=" + message + ", expected [" + expectedMessages + "]", match);
+
+				expectedMessages.remove(match);
+			}
+		}
+
+		private MessageExchange findMatch(List<MessageExchange> expectedMessages, Message<?> message) {
+			for (MessageExchange exchange : expectedMessages) {
+				if (exchange.matchMessage(message)) {
+					return exchange;
+				}
 			}
+			return null;
 		}
 	}