Sonar Fixes

https://sonar.spring.io/component_issues?id=org.springframework.integration%3Aspring-integration%3Amaster#resolved=false|types=BUG

In `IntegrationFlowRegistration` double check locking is ok for `inputChannel`
because we're assigning an existing object, but `MessagingTemplate` constructs
a new object for which double check locking doesn't work.

In any case, for both these items, the chance of concurrent access is extremely low
and is idempotent anyway, so remove double check locking.

Several inner classes can be static.

Other minor fixes.

Author: garyrussell

spring-integration-amqp/src/main/java/org/springframework/integration/amqp/outbound/AbstractAmqpOutboundEndpoint.java

@@ -349,7 +349,7 @@ public synchronized void start() {
 		if (!this.running) {
 			if (!this.lazyConnect && this.connectionFactory != null) {
 				try {
-					Connection connection = this.connectionFactory.createConnection();
+					Connection connection = this.connectionFactory.createConnection(); // NOSONAR (close)
 					if (connection != null) {
 						connection.close();
 					}

spring-integration-core/src/main/java/org/springframework/integration/channel/DefaultHeaderChannelRegistry.java

@@ -229,7 +229,7 @@ public synchronized void run() {
 	}
 
 
-	private final class MessageChannelWrapper {
+	private static final class MessageChannelWrapper {
 
 		private final MessageChannel channel;
 

spring-integration-core/src/main/java/org/springframework/integration/channel/QueueChannel.java

@@ -119,7 +119,7 @@ protected Message<?> doReceive(long timeout) {
 					long nanos = TimeUnit.MILLISECONDS.toNanos(timeout);
 					long deadline = System.nanoTime() + nanos;
 					while (this.queue.size() == 0 && nanos > 0) {
-						this.queueSemaphore.tryAcquire(nanos, TimeUnit.NANOSECONDS);
+						this.queueSemaphore.tryAcquire(nanos, TimeUnit.NANOSECONDS); // NOSONAR - ok to ignore result
 						nanos = deadline - System.nanoTime();
 					}
 					return this.queue.poll();

spring-integration-core/src/main/java/org/springframework/integration/config/annotation/ServiceActivatorAnnotationPostProcessor.java

@@ -84,7 +84,7 @@ protected MessageHandler createHandler(Object bean, Method method, List<Annotati
 		return serviceActivator;
 	}
 
-	private final class ReplyProducingMessageHandlerWrapper extends AbstractReplyProducingMessageHandler
+	private static final class ReplyProducingMessageHandlerWrapper extends AbstractReplyProducingMessageHandler
 			implements Lifecycle {
 
 		private final MessageHandler target;

spring-integration-core/src/main/java/org/springframework/integration/dsl/StandardIntegrationFlow.java

@@ -35,15 +35,15 @@ public class StandardIntegrationFlow implements IntegrationFlow, SmartLifecycle
 
 	private final List<SmartLifecycle> lifecycles = new LinkedList<SmartLifecycle>();
 
-	private final boolean registerComponents = true;
+	private final boolean registerComponents = true; // NOSONAR
 
 	private boolean running;
 
 	StandardIntegrationFlow(Set<Object> integrationComponents) {
 		this.integrationComponents = new LinkedList<Object>(integrationComponents);
 	}
 
-	//TODO Figure out some custom DestinationResolver when we don't register singletons
+	//TODO Figure out some custom DestinationResolver when we don't register singletons - remove NOSONAR above when done
 	/*public void setRegisterComponents(boolean registerComponents) {
 		this.registerComponents = registerComponents;
 	}*/

spring-integration-core/src/main/java/org/springframework/integration/dsl/context/IntegrationFlowRegistration.java

@@ -53,7 +53,7 @@ public class IntegrationFlowRegistration {
 	}
 
 	void setBeanFactory(ConfigurableListableBeanFactory beanFactory) {
-		this.beanFactory = beanFactory;
+		this.beanFactory = beanFactory; // NOSONAR (synchronization)
 	}
 
 	void setIntegrationFlowContext(IntegrationFlowContext integrationFlowContext) {
@@ -78,28 +78,24 @@ public IntegrationFlow getIntegrationFlow() {
 
 	public MessageChannel getInputChannel() {
 		if (this.inputChannel == null) {
-			synchronized (this) {
-				if (this.inputChannel == null) {
-					if (this.integrationFlow instanceof StandardIntegrationFlow) {
-						StandardIntegrationFlow integrationFlow = (StandardIntegrationFlow) this.integrationFlow;
-						Object next = integrationFlow.getIntegrationComponents().iterator().next();
-						if (next instanceof MessageChannel) {
-							this.inputChannel = (MessageChannel) next;
-						}
-						else {
-							throw new IllegalStateException("The 'IntegrationFlow' [" + integrationFlow + "] " +
-									"doesn't start with 'MessageChannel' for direct message sending.");
-						}
-					}
-					else {
-						throw new IllegalStateException("Only 'StandardIntegrationFlow' instances " +
-								"(e.g. extracted from 'IntegrationFlow' Lambdas) can be used " +
-								"for direct 'send' operation. " +
-								"But [" + this.integrationFlow + "] ins't one of them.\n" +
-								"Consider 'BeanFactory.getBean()' usage for sending messages " +
-								"to the required 'MessageChannel'.");
-					}
+			if (this.integrationFlow instanceof StandardIntegrationFlow) {
+				StandardIntegrationFlow integrationFlow = (StandardIntegrationFlow) this.integrationFlow;
+				Object next = integrationFlow.getIntegrationComponents().iterator().next();
+				if (next instanceof MessageChannel) {
+					this.inputChannel = (MessageChannel) next;
 				}
+				else {
+					throw new IllegalStateException("The 'IntegrationFlow' [" + integrationFlow + "] " +
+							"doesn't start with 'MessageChannel' for direct message sending.");
+				}
+			}
+			else {
+				throw new IllegalStateException("Only 'StandardIntegrationFlow' instances " +
+						"(e.g. extracted from 'IntegrationFlow' Lambdas) can be used " +
+						"for direct 'send' operation. " +
+						"But [" + this.integrationFlow + "] ins't one of them.\n" +
+						"Consider 'BeanFactory.getBean()' usage for sending messages " +
+						"to the required 'MessageChannel'.");
 			}
 		}
 		return this.inputChannel;
@@ -115,25 +111,21 @@ public MessageChannel getInputChannel() {
 	 */
 	public MessagingTemplate getMessagingTemplate() {
 		if (this.messagingTemplate == null) {
-			synchronized (this) {
-				if (this.messagingTemplate == null) {
-					this.messagingTemplate = new MessagingTemplate(getInputChannel()) {
-
-						@Override
-						public Message<?> receive() {
-							return receiveAndConvert(Message.class);
-						}
-
-						@Override
-						public <T> T receiveAndConvert(Class<T> targetClass) {
-							throw new UnsupportedOperationException("The 'receive()/receiveAndConvert()' " +
-									"isn't supported on the 'IntegrationFlow' input channel.");
-						}
-
-					};
-					this.messagingTemplate.setBeanFactory(this.beanFactory);
+			this.messagingTemplate = new MessagingTemplate(getInputChannel()) {
+
+				@Override
+				public Message<?> receive() {
+					return receiveAndConvert(Message.class);
 				}
-			}
+
+				@Override
+				public <T> T receiveAndConvert(Class<T> targetClass) {
+					throw new UnsupportedOperationException("The 'receive()/receiveAndConvert()' " +
+							"isn't supported on the 'IntegrationFlow' input channel.");
+				}
+
+			};
+			this.messagingTemplate.setBeanFactory(this.beanFactory);
 		}
 		return this.messagingTemplate;
 	}

spring-integration-core/src/main/java/org/springframework/integration/store/SimpleMessageStore.java

@@ -278,13 +278,13 @@ public void addMessagesToGroup(Object groupId, Message<?>... messages) {
 						throw outOfCapacityException;
 					}
 					group = getMessageGroupFactory().create(groupId);
-					this.groupIdToMessageGroup.putIfAbsent(groupId, group);
+					this.groupIdToMessageGroup.put(groupId, group);
 					upperBound = new UpperBound(this.groupCapacity);
 					for (Message<?> message : messages) {
 						upperBound.tryAcquire(-1);
 						group.add(message);
 					}
-					this.groupToUpperBound.putIfAbsent(groupId, upperBound);
+					this.groupToUpperBound.put(groupId, upperBound);
 				}
 				else {
 					upperBound = this.groupToUpperBound.get(groupId);

spring-integration-core/src/main/java/org/springframework/integration/support/converter/SimpleMessageConverter.java

@@ -141,7 +141,7 @@ public Message<?> toMessage(Object object) throws Exception {
 	}
 
 
-	private class DefaultOutboundMessageMapper implements OutboundMessageMapper<Object> {
+	private static class DefaultOutboundMessageMapper implements OutboundMessageMapper<Object> {
 
 		DefaultOutboundMessageMapper() {
 			super();

spring-integration-core/src/main/java/org/springframework/integration/util/SimplePool.java

@@ -122,18 +122,22 @@ public synchronized void setPoolSize(int poolSize) {
 	 * if it was recently reduced and too many items were in use to allow the new size
 	 * to be set.
 	 */
-	public int getPoolSize() {
+	@Override
+	public synchronized int getPoolSize() {
 		return this.poolSize.get();
 	}
 
+	@Override
 	public int getIdleCount() {
 		return this.available.size();
 	}
 
+	@Override
 	public int getActiveCount() {
 		return this.inUse.size();
 	}
 
+	@Override
 	public int getAllocatedCount() {
 		return this.allocated.size();
 	}
@@ -153,6 +157,7 @@ public void setWaitTimeout(long waitTimeout) {
 	 * Obtains an item from the pool; waits up to waitTime milliseconds (default infinity).
 	 * @throws MessagingException if no items become available in time.
 	 */
+	@Override
 	public T getItem() {
 		boolean permitted = false;
 		try {
@@ -205,6 +210,7 @@ else if (this.callback.isStale(item)) {
 	/**
 	 * Returns an item to the pool.
 	 */
+	@Override
 	public synchronized void releaseItem(T item) {
 		Assert.notNull(item, "Item cannot be null");
 		Assert.isTrue(this.allocated.contains(item),
@@ -234,6 +240,7 @@ public synchronized void releaseItem(T item) {
 		}
 	}
 
+	@Override
 	public synchronized void removeAllIdleItems() {
 		T item;
 		while ((item = this.available.poll()) != null) {

spring-integration-http/src/main/java/org/springframework/integration/http/config/IntegrationGraphControllerRegistrar.java

@@ -119,7 +119,7 @@ private static final class IntegrationGraphCorsConfigurer extends WebMvcConfigur
 
 		private final String[] allowedOrigins;
 
-		private IntegrationGraphCorsConfigurer(String path, String[] allowedOrigins) {
+		private IntegrationGraphCorsConfigurer(String path, String[] allowedOrigins) { // NOSONAR
 			this.path = path;
 			this.allowedOrigins = allowedOrigins;
 		}