GH-1080: SMLC: Fix concurrency configuration order

Fixes #1080

When we have a configuration like this:
```
container.setConcurrentConsumers(1);
container.setMaxConcurrentConsumers(1);
container.setConcurrency("2-5");
```
we fail with an assertion like
`'concurrentConsumers' cannot be more than 'maxConcurrentConsumers'`

* Change the order in the `SimpleMessageListenerContainer.setConcurrency()`
how we populate `maxConcurrentConsumers` and `concurrentConsumers`

**Cherry-pick to 2.1.x and 1.7.x**

* * Reset `concurrentConsumers` and `maxConcurrentConsumers` to their
default before parsing `concurrency` string

* * Validate concurrency values before setting into properties

* * Reset old values and call setters for concurrency bits

* Fix AssertJ structures in the `MessageListenerContainerLifecycleIntegrationTests`

Author: artembilan

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/SimpleMessageListenerContainer.java

@@ -212,9 +212,14 @@ public void setConcurrency(String concurrency) {
 		try {
 			int separatorIndex = concurrency.indexOf('-');
 			if (separatorIndex != -1) {
-				setConcurrentConsumers(Integer.parseInt(concurrency.substring(0, separatorIndex)));
-				setMaxConcurrentConsumers(
-						Integer.parseInt(concurrency.substring(separatorIndex + 1, concurrency.length())));
+				int concurrentConsumers = Integer.parseInt(concurrency.substring(0, separatorIndex));
+				int maxConcurrentConsumers = Integer.parseInt(concurrency.substring(separatorIndex + 1));
+				Assert.isTrue(maxConcurrentConsumers >= concurrentConsumers,
+						"'maxConcurrentConsumers' value must be at least 'concurrentConsumers'");
+				this.concurrentConsumers = 1;
+				this.maxConcurrentConsumers = null;
+				setConcurrentConsumers(concurrentConsumers);
+				setMaxConcurrentConsumers(maxConcurrentConsumers);
 			}
 			else {
 				setConcurrentConsumers(Integer.parseInt(concurrency));

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

@@ -477,6 +477,16 @@ public void testLongLivingConsumerStoppedProperlyAfterContextClose() throws Exce
 		((DisposableBean) template.getConnectionFactory()).destroy();
 	}
 
+	@Test
+	public void testConcurrencyConfiguration() {
+		SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
+		container.setConcurrentConsumers(1);
+		container.setMaxConcurrentConsumers(1);
+		container.setConcurrency("2-5");
+
+		assertEquals(2, TestUtils.getPropertyValue(container, "concurrentConsumers"));
+		assertEquals(5, TestUtils.getPropertyValue(container, "maxConcurrentConsumers"));
+	}
 
 	@Configuration
 	static class LongLiveConsumerConfig {