GH-1108: @QueueBinding.key recursive resolution

Fixes #1108

`@RabbitListener.queues()` resolves `String[]` recursively.
AMQP-722 added support for multiple routing keys to `@queueBinding` but
did not add support for recursive resolution. This is required to support
constructs like `key = "#{'${my-app.amqp.routing-key}'.split(',')}"`.

**cherry-pick to 2.1.x**

# Conflicts:
#	spring-rabbit/src/test/java/org/springframework/amqp/rabbit/annotation/RabbitListenerAnnotationBeanPostProcessorTests.java

Fix test

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/annotation/RabbitListenerAnnotationBeanPostProcessor.java

@@ -503,7 +503,7 @@ private String[] resolveQueues(RabbitListener rabbitListener) {
 		List<String> result = new ArrayList<String>();
 		if (queues.length > 0) {
 			for (int i = 0; i < queues.length; i++) {
-				resolveAsString(resolveExpression(queues[i]), result);
+				resolveAsString(resolveExpression(queues[i]), result, true, "queues");
 			}
 		}
 		if (queuesToDeclare.length > 0) {
@@ -526,25 +526,28 @@ private String[] resolveQueues(RabbitListener rabbitListener) {
 	}
 
 	@SuppressWarnings("unchecked")
-	private void resolveAsString(Object resolvedValue, List<String> result) {
+	private void resolveAsString(Object resolvedValue, List<String> result, boolean canBeQueue, String what) {
 		Object resolvedValueToUse = resolvedValue;
 		if (resolvedValue instanceof String[]) {
 			resolvedValueToUse = Arrays.asList((String[]) resolvedValue);
 		}
-		if (resolvedValueToUse instanceof Queue) {
+		if (canBeQueue && resolvedValueToUse instanceof Queue) {
 			result.add(((Queue) resolvedValueToUse).getName());
 		}
 		else if (resolvedValueToUse instanceof String) {
 			result.add((String) resolvedValueToUse);
 		}
 		else if (resolvedValueToUse instanceof Iterable) {
 			for (Object object : (Iterable<Object>) resolvedValueToUse) {
-				resolveAsString(object, result);
+				resolveAsString(object, result, canBeQueue, what);
 			}
 		}
 		else {
 			throw new IllegalArgumentException(String.format(
-					"@RabbitListener can't resolve '%s' as either a String or a Queue",
+					"@RabbitListener."
+					+ what
+					+ " can't resolve '%s' as a String[] or a String "
+					+ (canBeQueue ? "or a Queue" : ""),
 					resolvedValue));
 		}
 	}
@@ -632,15 +635,15 @@ private void declareExchangeAndBinding(QueueBinding binding, String queueName) {
 	}
 
 	private void registerBindings(QueueBinding binding, String queueName, String exchangeName, String exchangeType) {
-		final String[] routingKeys;
+		final List<String> routingKeys;
 		if (exchangeType.equals(ExchangeTypes.FANOUT) || binding.key().length == 0) {
-			routingKeys = new String[] { "" };
+			routingKeys = Collections.singletonList("");
 		}
 		else {
 			final int length = binding.key().length;
-			routingKeys = new String[length];
+			routingKeys = new ArrayList<>();
 			for (int i = 0; i < length; ++i) {
-				routingKeys[i] = resolveExpressionAsString(binding.key()[i], "@QueueBinding.key");
+				resolveAsString(resolveExpression(binding.key()[i]), routingKeys, false, "@QueueBinding.key");
 			}
 		}
 		final Map<String, Object> bindingArguments = resolveArguments(binding.arguments());

spring-rabbit/src/test/java/org/springframework/amqp/rabbit/annotation/RabbitListenerAnnotationBeanPostProcessorTests.java

@@ -208,8 +208,8 @@ public void invalidValueInAnnotationTestBean() {
 		catch (BeanCreationException e) {
 			assertThat(e.getCause(), instanceOf(IllegalArgumentException.class));
 			assertThat(e.getMessage(), allOf(
-					containsString("@RabbitListener can't resolve"),
-					containsString("as either a String or a Queue")
+					containsString("@RabbitListener.queues can't resolve"),
+					containsString("as a String[] or a String or a Queue")
 					));
 		}
 	}
@@ -233,10 +233,11 @@ public void multipleRoutingKeysTestBean() {
 		assertThat(context.getBeansOfType(org.springframework.amqp.core.Exchange.class).values(), hasSize(1));
 
 		final List<Binding> bindings = new ArrayList<>(context.getBeansOfType(Binding.class).values());
-		assertThat(bindings, hasSize(2));
+		assertThat(bindings, hasSize(3));
 		bindings.sort(Comparator.comparing(Binding::getRoutingKey));
-		assertEquals("Binding [destination=my_queue, exchange=my_exchange, routingKey=red]", bindings.get(0).toString());
-		assertEquals("Binding [destination=my_queue, exchange=my_exchange, routingKey=yellow]", bindings.get(1).toString());
+		assertEquals("Binding [destination=my_queue, exchange=my_exchange, routingKey=green]", bindings.get(0).toString());
+		assertEquals("Binding [destination=my_queue, exchange=my_exchange, routingKey=red]", bindings.get(1).toString());
+		assertEquals("Binding [destination=my_queue, exchange=my_exchange, routingKey=yellow]", bindings.get(2).toString());
 
 		context.close();
 	}
@@ -394,8 +395,9 @@ public void handleIt(String body) {
 	static class MultipleRoutingKeysTestBean {
 
 		@RabbitListener(bindings = @QueueBinding(exchange = @Exchange("my_exchange"),
-				value = @org.springframework.amqp.rabbit.annotation.Queue(value = "my_queue", arguments = @Argument(name = "foo", value = "bar")),
-				key = {"${xxxxxxx:red}", "yellow"}))
+				value = @org.springframework.amqp.rabbit.annotation.Queue(value = "my_queue",
+					arguments = @Argument(name = "foo", value = "bar")),
+				key = {"${xxxxxxx:red}", "#{'yellow,green'.split(',')}"}))
 		public void handleIt(String body) {
 		}
 	}