GH-1059: Add SpEL support for KafkaListener.id()

Fixes #1059

* Code style polishing in the `KafkaListenerAnnotationBeanPostProcessor`
 and `EnableKafkaIntegrationTests`

**Cherry-pick to 2.2.x**

Author: artembilan

spring-kafka/src/main/java/org/springframework/kafka/annotation/KafkaListenerAnnotationBeanPostProcessor.java

@@ -277,14 +277,9 @@ public Object postProcessAfterInitialization(final Object bean, final String bea
 			final boolean hasClassLevelListeners = classLevelListeners.size() > 0;
 			final List<Method> multiMethods = new ArrayList<>();
 			Map<Method, Set<KafkaListener>> annotatedMethods = MethodIntrospector.selectMethods(targetClass,
-					new MethodIntrospector.MetadataLookup<Set<KafkaListener>>() {
-
-						@Override
-						public Set<KafkaListener> inspect(Method method) {
-							Set<KafkaListener> listenerMethods = findListenerAnnotations(method);
-							return (!listenerMethods.isEmpty() ? listenerMethods : null);
-						}
-
+					(MethodIntrospector.MetadataLookup<Set<KafkaListener>>) method -> {
+						Set<KafkaListener> listenerMethods = findListenerAnnotations(method);
+						return (!listenerMethods.isEmpty() ? listenerMethods : null);
 					});
 			if (hasClassLevelListeners) {
 				Set<Method> methodsWithHandler = MethodIntrospector.selectMethods(targetClass,
@@ -427,8 +422,7 @@ protected void processListener(MethodKafkaListenerEndpoint<?, ?> endpoint, Kafka
 		endpoint.setTopicPartitions(resolveTopicPartitions(kafkaListener));
 		endpoint.setTopics(resolveTopics(kafkaListener));
 		endpoint.setTopicPattern(resolvePattern(kafkaListener));
-		endpoint.setClientIdPrefix(resolveExpressionAsString(kafkaListener.clientIdPrefix(),
-				"clientIdPrefix"));
+		endpoint.setClientIdPrefix(resolveExpressionAsString(kafkaListener.clientIdPrefix(), "clientIdPrefix"));
 		String group = kafkaListener.containerGroup();
 		if (StringUtils.hasText(group)) {
 			Object resolvedGroup = resolveExpression(group);
@@ -475,11 +469,14 @@ private void resolveKafkaProperties(MethodKafkaListenerEndpoint<?, ?> endpoint,
 		if (propertyStrings.length > 0) {
 			Properties properties = new Properties();
 			for (String property : propertyStrings) {
-				try {
-					properties.load(new StringReader(resolveExpressionAsString(property, "property")));
-				}
-				catch (IOException e) {
-					this.logger.error("Failed to load property " + property + ", continuing...", e);
+				String value = resolveExpressionAsString(property, "property");
+				if (value != null) {
+					try {
+						properties.load(new StringReader(value));
+					}
+					catch (IOException e) {
+						this.logger.error("Failed to load property " + property + ", continuing...", e);
+					}
 				}
 			}
 			endpoint.setConsumerProperties(properties);
@@ -488,7 +485,7 @@ private void resolveKafkaProperties(MethodKafkaListenerEndpoint<?, ?> endpoint,
 
 	private String getEndpointId(KafkaListener kafkaListener) {
 		if (StringUtils.hasText(kafkaListener.id())) {
-			return resolve(kafkaListener.id());
+			return resolveExpressionAsString(kafkaListener.id(), "id");
 		}
 		else {
 			return GENERATED_ID_PREFIX + this.counter.getAndIncrement();
@@ -514,19 +511,19 @@ private TopicPartitionInitialOffset[] resolveTopicPartitions(KafkaListener kafka
 				result.addAll(resolveTopicPartitionsList(topicPartition));
 			}
 		}
-		return result.toArray(new TopicPartitionInitialOffset[result.size()]);
+		return result.toArray(new TopicPartitionInitialOffset[0]);
 	}
 
 	private String[] resolveTopics(KafkaListener kafkaListener) {
 		String[] topics = kafkaListener.topics();
 		List<String> result = new ArrayList<>();
 		if (topics.length > 0) {
-			for (int i = 0; i < topics.length; i++) {
-				Object topic = resolveExpression(topics[i]);
+			for (String topic1 : topics) {
+				Object topic = resolveExpression(topic1);
 				resolveAsString(topic, result);
 			}
 		}
-		return result.toArray(new String[result.size()]);
+		return result.toArray(new String[0]);
 	}
 
 	private Pattern resolvePattern(KafkaListener kafkaListener) {
@@ -558,8 +555,8 @@ private List<TopicPartitionInitialOffset> resolveTopicPartitionsList(TopicPartit
 		Assert.state(partitions.length > 0 || partitionOffsets.length > 0,
 				"At least one 'partition' or 'partitionOffset' required in @TopicPartition for topic '" + topic + "'");
 		List<TopicPartitionInitialOffset> result = new ArrayList<>();
-		for (int i = 0; i < partitions.length; i++) {
-			resolvePartitionAsInteger((String) topic, resolveExpression(partitions[i]), result);
+		for (String partition : partitions) {
+			resolvePartitionAsInteger((String) topic, resolveExpression(partition), result);
 		}
 
 		for (PartitionOffset partitionOffset : partitionOffsets) {

spring-kafka/src/test/java/org/springframework/kafka/annotation/EnableKafkaIntegrationTests.java

@@ -17,7 +17,7 @@
 package org.springframework.kafka.annotation;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.mockito.ArgumentMatchers.anyMap;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.isNull;
@@ -255,7 +255,7 @@ public void testSimple() throws Exception {
 				"listenerConsumer.consumer"));
 		assertThat(
 				KafkaTestUtils.getPropertyValue(this.listener.listen4Consumer, "fetcher.maxPollRecords", Integer.class))
-						.isEqualTo(100);
+				.isEqualTo(100);
 		assertThat(this.quxGroup).hasSize(1);
 		assertThat(this.quxGroup.get(0)).isSameAs(manualContainer);
 		List<?> containers = KafkaTestUtils.getPropertyValue(manualContainer, "containers", List.class);
@@ -309,14 +309,12 @@ public void testSimple() throws Exception {
 				.isNotEqualTo("rebalanceListener");
 		String clientId = KafkaTestUtils.getPropertyValue(rebalanceContainer, "listenerConsumer.consumer.clientId",
 				String.class);
-		assertThat(
-				clientId)
-				.startsWith("rebal-");
+		assertThat(clientId).startsWith("rebal-");
 		assertThat(clientId.indexOf('-')).isEqualTo(clientId.lastIndexOf('-'));
 	}
 
 	@Test
-	public void testAutoStartup() throws Exception {
+	public void testAutoStartup() {
 		MessageListenerContainer listenerContainer = registry.getListenerContainer("manualStart");
 		assertThat(listenerContainer).isNotNull();
 		assertThat(listenerContainer.isRunning()).isFalse();
@@ -399,7 +397,6 @@ public void testJson() throws Exception {
 	}
 
 	@Test
-	@DirtiesContext
 	public void testJsonHeaders() throws Exception {
 		ConcurrentMessageListenerContainer<?, ?> container =
 				(ConcurrentMessageListenerContainer<?, ?>) registry.getListenerContainer("jsonHeaders");
@@ -546,7 +543,7 @@ public void testValidation() throws Exception {
 	}
 
 	@Test
-	public void testReplyingListener() throws Exception {
+	public void testReplyingListener() {
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -560,7 +557,7 @@ public void testReplyingListener() throws Exception {
 	}
 
 	@Test
-	public void testReplyingBatchListener() throws Exception {
+	public void testReplyingBatchListener() {
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testBatchReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -586,7 +583,7 @@ public void testReplyingBatchListener() throws Exception {
 	}
 
 	@Test
-	public void testReplyingListenerWithErrorHandler() throws Exception {
+	public void testReplyingListenerWithErrorHandler() {
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testErrorHandlerReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -600,7 +597,7 @@ public void testReplyingListenerWithErrorHandler() throws Exception {
 	}
 
 	@Test
-	public void testVoidListenerWithReplyingErrorHandler() throws Exception {
+	public void testVoidListenerWithReplyingErrorHandler() {
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testVoidWithErrorHandlerReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -614,7 +611,7 @@ public void testVoidListenerWithReplyingErrorHandler() throws Exception {
 	}
 
 	@Test
-	public void testReplyingBatchListenerWithErrorHandler() throws Exception {
+	public void testReplyingBatchListenerWithErrorHandler() {
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testErrorHandlerBatchReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -640,7 +637,7 @@ public void testReplyingBatchListenerWithErrorHandler() throws Exception {
 	}
 
 	@Test
-	public void testMultiReplyTo() throws Exception {
+	public void testMultiReplyTo() {
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testMultiReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -709,10 +706,12 @@ public void testAddingTopics() {
 		assertThat(embeddedKafka.getTopics().size()).isEqualTo(count + 1);
 		embeddedKafka.addTopics(new NewTopic("morePartitions", 10, (short) 1));
 		assertThat(embeddedKafka.getTopics().size()).isEqualTo(count + 2);
-		assertThatThrownBy(() -> embeddedKafka.addTopics(new NewTopic("morePartitions", 10, (short) 1)))
-			.isInstanceOf(IllegalArgumentException.class).hasMessageContaining("exists");
-		assertThatThrownBy(() -> embeddedKafka.addTopics(new NewTopic("morePartitions2", 10, (short) 2)))
-			.isInstanceOf(IllegalArgumentException.class).hasMessageContaining("replication");
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> embeddedKafka.addTopics(new NewTopic("morePartitions", 10, (short) 1)))
+				.withMessageContaining("exists");
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> embeddedKafka.addTopics(new NewTopic("morePartitions2", 10, (short) 2)))
+				.withMessageContaining("replication");
 		Map<String, Object> consumerProps = new HashMap<>(this.consumerFactory.getConfigurationProperties());
 		consumerProps.put(ConsumerConfig.GROUP_ID_CONFIG, "testMultiReplying");
 		ConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -733,7 +732,7 @@ public void testReceivePollResults() throws Exception {
 	@Test
 	public void testAutoConfigTm() {
 		assertThat(this.transactionalFactory.getContainerProperties().getTransactionManager())
-			.isInstanceOf(ChainedKafkaTransactionManager.class);
+				.isInstanceOf(ChainedKafkaTransactionManager.class);
 	}
 
 	@Test
@@ -1416,8 +1415,9 @@ public void listen3(ConsumerRecord<?, ?> record) {
 			this.latch3.countDown();
 		}
 
-		@KafkaListener(id = "qux", topics = "annotated4", containerFactory = "kafkaManualAckListenerContainerFactory",
-				containerGroup = "qux#{'Group'}", properties = {
+		@KafkaListener(id = "#{'qux'}", topics = "annotated4",
+				containerFactory = "kafkaManualAckListenerContainerFactory", containerGroup = "qux#{'Group'}",
+				properties = {
 						"max.poll.interval.ms:#{'${poll.interval:60000}'}",
 						ConsumerConfig.MAX_POLL_RECORDS_CONFIG + "=#{'${poll.recs:100}'}"
 				})
@@ -1879,6 +1879,7 @@ public void setDelegate(
 		public Foo convert(String source) {
 			return delegate.convert(source);
 		}
+
 	}
 
 	public static class ValidatedClass {